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  • 51.
    Felleki, Majbritt
    Dalarna University, School of Technology and Business Studies, Statistics. Swedish University of Agricultural Sciences.
    Genetic Heteroscedasticity for Domestic Animal Traits2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Animal traits differ not only in mean, but also in variation around the mean. For instance, one sire’s daughter group may be very homogeneous, while another sire’s daughters are much more heterogeneous in performance. The difference in residual variance can partially be explained by genetic differences. Models for such genetic heterogeneity of environmental variance include genetic effects for the mean and residual variance, and a correlation between the genetic effects for the mean and residual variance to measure how the residual variance might vary with the mean.

    The aim of this thesis was to develop a method based on double hierarchical generalized linear models for estimating genetic heteroscedasticity, and to apply it on four traits in two domestic animal species; teat count and litter size in pigs, and milk production and somatic cell count in dairy cows.

    The method developed is fast and has been implemented in software that is widely used in animal breeding, which makes it convenient to use. It is based on an approximation of double hierarchical generalized linear models by normal distributions. When having repeated observations on individuals or genetic groups, the estimates were found to be unbiased.

    For the traits studied, the estimated heritability values for the mean and the residual variance, and the genetic coefficients of variation, were found in the usual ranges reported. The genetic correlation between mean and residual variance was estimated for the pig traits only, and was found to be favorable for litter size, but unfavorable for teat count.

  • 52.
    Felleki, Majbritt
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Chalkias, Helena
    A Double Hierarchical Generalized Linear Model For Teat Number In Pigs2010Conference paper (Other academic)
  • 53.
    Felleki, Majbritt
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Lee, Dongwhan
    Department of Statistics, Seoul National University, Seoul 151-747, Korea .
    Lee, Youngjo
    Department of Statistics, Seoul National University, Seoul 151-747, Korea .
    Gilmour, Arthur R.
    School of Mathematics and Applied Statistics, Faculty of Informatics, University of Wollongong, Wollongong, NSW 2522, Australia.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Estimation of breeding values for mean and dispersion, their variance and correlation using double hierarchical generalized linear models2012In: Genetics Research, ISSN 0016-6723, Vol. 94, no 6, p. 307-317Article in journal (Refereed)
    Abstract [en]

    The possibility of breeding for uniform individuals by selecting animals expressing a small response to environment has been studied extensively in animal breeding. Bayesian methods for fitting models with genetic components in the residual variance have been developed for this purpose, but have limitations due to the computational demands. We use the hierarchical (h)-likelihood from the theory of double hierarchical generalized linear models (DHGLM) to derive an estimation algorithm that is computationally feasible for large datasets. Random effects for both the mean and residual variance parts of the model are estimated together with their variance/covariance components. An important feature of the algorithm is that it can fit a correlation between the random effects for mean and variance. An h-likelihood estimator is implemented in the R software and an iterative reweighted least square (IRWLS) approximation of the h-likelihood is implemented using ASReml. The difference in variance component estimates between the two implementations is investigated, as well as the potential bias of the methods, using simulations. IRWLS gives the same results as h-likelihood in simple cases with no severe indication of bias. For more complex cases, only IRWLS could be used, and bias did appear. The IRWLS is applied on the pig litter size data previously analysed by Sorensen & Waagepetersen (2003) using Bayesian methodology. The estimates we obtained by using IRWLS are similar to theirs, with the estimated correlation between the random genetic effects being −0·52 for IRWLS and −0·62 in Sorensen & Waagepetersen (2003).

  • 54.
    Felleki, Majbritt
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics. Sveriges Lantbruksuniversitet.
    Lundeheim, Nils
    Sveriges Lantbruksuniversitet.
    Genetic Control of Residual Variance for Teat Number in Pigs2013In: Proc. Assoc. Advmt. Anim. Breed. Genet., AAABG , 2013, p. 538-541Conference paper (Other academic)
    Abstract [en]

    The genetic improvement in litter size in pigs has been substantial during the last 10-15 years. The number of teats on the sow must increase as well to meet the needs of the piglets, because each piglet needs access to its own teat. We applied a genetic heterogeneity model on teat numberin sows, and estimated medium-high heritability for teat number (0.5), but low heritability for residual variance (0.05), indicating that selection for reduced variance might have very limited effect. A numerically positive correlation (0.8) between additive genetic breeding values for mean and for variance was found, but because of the low heritability for residual variance, the variance will increase very slowly with the mean.

  • 55.
    Felleki, Majbritt
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Lundeheim, Nils
    Sveriges lantbruksuniversitet, Institutionen för husdjursgenetik.
    Genetic Heteroscedasticity for Teat Count in PigsManuscript (preprint) (Other academic)
  • 56.
    Felleki, Majbritt
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Lundeheim, Nils
    SLU.
    Genetic heteroscedasticity of teat count in pigs2015In: Journal of Animal Breeding and Genetics, ISSN 0931-2668, E-ISSN 1439-0388, Vol. 132, no 5, p. 392-398Article in journal (Refereed)
    Abstract [en]

    The genetic improvement in pig litter size has been substantial. The number of teats on the sowmust thus increase as well to meet the needs of the piglets, because each piglet needs access to itsown teat. We applied a genetic heterogeneity model to teat counts in pigs, and estimated a mediumheritability for teat counts (0.35), but found a low heritability for residual variance (0.06),indicating that selection for reduced residual variance might have a limited effect. A numericallypositive correlation (0.8) was estimated between the breeding values for the mean and the residualvariance. However, because of the low heritability of the residual variance, the residual variance will probably increase very slowly with the mean.

  • 57.
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Statistics.
    Computational study of the step size parameter of the subgradient optimization methodManuscript (preprint) (Other academic)
    Abstract [en]

    The subgradient optimization method is a simple and flexible linear programming iterative algorithm. It is much simpler than Newton's method and can be applied to a wider variety of problems. It also converges when the objective function is non-differentiable. Since an efficient algorithm will not only produce a good solution but also take less computing time, we always prefer a simpler algorithm with high quality. In this study a series of step size parameters in the subgradient equation is studied. The performance is compared for a general piecewise function and a specific p-median problem. We examine how the quality of solution changes by setting five forms of step size parameter.

  • 58.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Lundmark, M.
    Intra-urban location of stores and labour turnover in retail2019In: International Review of Retail Distribution & Consumer Research, ISSN 0959-3969, E-ISSN 1466-4402Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to analyse labour turnover in retail firms with stores in different city locations. This case study of a Swedish mid-sized city uses comprehensive longitudinal register data on individuals. In a first step, an unconditional descriptive analysis shows that labour turnover in retail is higher in out-of-town locations, compared to more central locations in the city. In a second step, a generalized linear model (GLM) analysis is conducted where labour turnover in downtown and out-of-town locations are compared. Firm internal and industry factors, as well as employee characteristics, and location-specific factors are controlled for. The results indicate that commuting costs and intra-urban location have no statistically significant effect on labour turnover in retail firms. Instead, firm internal factors, such as human resource management, has a major influence on labour turnover rates. The findings indicate that in particular firms with multiple locations may need to pay extra attention to work conditions across stores in different places in a city, in order to avoid diverging levels of labour mobility. This paper complements previous survey-based studies on labour turnover by using a comprehensive micro-level dataset to analyse revealed rather than stated preferences concerning job-to-job mobility. An elaborated measure of labour turnover is used to analyse differences between shopping areas in different locations within the city. The particular research design used in this paper makes it possible to isolate the effect of intra-organizational conditions by analysing mobility within firms with workplaces in both downtown and out-of-town locations. This is the first comprehensive study of labour turnover and mobility with an intra-urban perspective in the retail sector.

  • 59.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Håkansson, Johan
    Dalarna University, School of Humanities and Media Studies, Cultural Studies.
    Rebreyend, Pascal
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    How do different densities in a network affect the optimal location of service centers?2013Report (Other academic)
    Abstract [en]

    The p-median problem is often used to locate p service centers by minimizing their distances to a geographically distributed demand (n). The optimal locations are sensitive to geographical context such as road network and demand points especially when they are asymmetrically distributed in the plane. Most studies focus on evaluating performances of the p-median model when p and n vary. To our knowledge this is not a very well-studied problem when the road network is alternated especially when it is applied in a real world context. The aim in this study is to analyze how the optimal location solutions vary, using the p-median model, when the density in the road network is alternated. The investigation is conducted by the means of a case study in a region in Sweden with an asymmetrically distributed population (15,000 weighted demand points), Dalecarlia. To locate 5 to 50 service centers we use the national transport administrations official road network (NVDB). The road network consists of 1.5 million nodes. To find the optimal location we start with 500 candidate nodes in the network and increase the number of candidate nodes in steps up to 67,000. To find the optimal solution we use a simulated annealing algorithm with adaptive tuning of the temperature. The results show that there is a limited improvement in the optimal solutions when nodes in the road network increase and p is low. When p is high the improvements are larger. The results also show that choice of the best network depends on p. The larger p the larger density of the network is needed. 

  • 60.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Human Geography.
    Rebreyend, Pascal
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    How does the use of different road networks effect the optimal location of facilities in rural areas?2012Report (Other academic)
    Abstract [en]

    The p-median problem is often used to locate P service facilities in a geographically distributed population. Important for the performance of such a model is the distance measure.

    Distance measure can vary if the accuracy of the road network varies. The rst aim in this study is to analyze how the optimal location solutions vary, using the p-median model, when the road network is alternated. It is hard to nd an exact optimal solution for p-median problems. Therefore, in this study two heuristic solutions are applied, simulating annealing and a classic heuristic. The secondary aim is to compare the optimal location solutions using dierent algorithms for large p-median problem. The investigation is conducted by the means of a case study in a rural region with an asymmetrically distributed population, Dalecarlia.

    The study shows that the use of more accurate road networks gives better solutions for optimal location, regardless what algorithm that is used and regardless how many service facilities that is optimized for. It is also shown that the simulated annealing algorithm not just is much faster than the classic heuristic used here, but also in most cases gives better location solutions.

  • 61.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Human Geography.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    How do neighbouring populations affect local population change over time?2013Report (Other academic)
    Abstract [en]

    This study covers a period when society changed from a pre-industrial agricultural society to a post-industrial service-producing society. Parallel with this social transformation, major population changes took place. In this study, we analyse how local population changes are affected by neighbouring populations. To do so we use the last 200 years of local population change that redistributed population in Sweden. We use literature to identify several different processes and spatial dependencies in the redistribution between a parish and its surrounding parishes. The analysis is based on a unique unchanged historical parish division, and we use an index of local spatial correlation to describe different kinds of spatial dependencies that have influenced the redistribution of the population. To control inherent time dependencies, we introduce a non-separable spatial temporal correlation model into the analysis of population redistribution. Hereby, several different spatial dependencies can be observed simultaneously over time. The main conclusions are that while local population changes have been highly dependent on the neighbouring populations in the 19th century, this spatial dependence have become insignificant already when two parishes is separated by 5 kilometres in the late 20th century. Another conclusion is that the time dependency in the population change is higher when the population redistribution is weak, as it currently is and as it was during the 19th century until the start of industrial revolution.

  • 62.
    Han, Mengjie
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics. HUI Research.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Information Systems. Dalarna University, School of Technology and Business Studies, Human Geography. HUI Research, Stockholm.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics. HUI Research, Stockholm.
    To what extent do neighbouring populations affect local population growth over time?2016In: Population, Space and Place, ISSN 1544-8444, E-ISSN 1544-8452, Vol. 22, no 1, p. 68-83Article in journal (Refereed)
    Abstract [en]

    This study covers a period when society changed from a pre-industrial agricultural society to a post-industrial service-producing society. Parallel with this social transformation, major population changes took place. In this study, we analyse to what extent local population change is affected by neighbouring populations. To do this, we focused on the last 190 years of local population change that redistributed population in Sweden. We used literature to identify several different processes in the population redistribution. The different processes implied different spatial dependencies between local population change and the surrounding populations. The analysis is based on an unchanged historical parish division, and we used an index of local spatial correlation to describe different types of spatial dependencies that influenced the redistribution of the population. To control inherent time dependencies, we introduced a non-separable spatial-temporal correlation model into the analysis of population redistribution. Hereby, several different spatial dependencies could be simultaneously observed over time. The main conclusions are that while local population changes have been highly dependent on neighbouring populations in the 19th century, this spatial dependence became insignificant already when two parishes are separated by 5 km in the late 20th century. It is argued that the only process that significantly redistributed the population at the end of the 20th century is the immigration to Sweden.

  • 63.
    Hartikainen Ritter, Jenny
    Dalarna University, School of Education, Health and Social Studies, Educational Work.
    Matematikundervisning med digitala verktyg2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie handlar om hur lärare kan arbeta med digitala verktyg inom matematik och vilka hinder eller möjligheter som finns när digitala verktyg används. För att besvara frågeställningarna söktes artiklar i databasenra ERIC-ebsco, SwePub och LIBRIS. I bakgrunden framkommer hur matematikundervisningen ser ut i skolan och om vilken betydelse och ansvar lärarna har. Studiens metod är en litteraturstudie, vilket betyder att resultaten söks i olika forskares studier.

    Resultatet visar på vilka hinder och möjligheter det finns med att använda digitala verktyg samt möjligheter med att använda digitala verktyg vid bedömning av elevers kunskap i ämnet matematik. Resultatet visar även att det finns hinder med lärarnas bristande kunskaper och osäkerhet om hur de kan använda digitala verktyg i matematikundervisningen.

  • 64.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics. Tianjin University of Finance and Economics.
    Kang, Jian
    Teräsvirta, Timo
    Zhang, Shuhua
    The shifting seasonal mean autoregressive model and seasonality in the Central England monthly temperature series, 1772–20162019In: Econometrics and Statistics, ISSN 2452-3062Article in journal (Refereed)
    Abstract [en]

    A new autoregressive model with seasonal dummy variables in which coefficients of seasonal dummies vary smoothly and deterministically over time is introduced. The error variance of the model is seasonally heteroskedastic and multiplicatively decomposed as in ARCH models. This variance is also allowed to be smoothly and deterministically time-varying. Under regularity conditions, consistency and asymptotic normality of the maximum likelihood estimators of parameters of this model is proved. The purpose of the model is to find out how the average monthly temperatures in the well-known central England temperature series have been varying during the period of more than 240 years. The main result is that warming has occurred but that there are notable differences between months. In particular, no warming is found for February, April, May and June.

  • 65.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Sandberg, Rickard
    Testing parameter constancy in unit root autoregressive models against multiple continuous structural changes2012In: Econometric Reviews, ISSN 0747-4938, E-ISSN 1532-4168, Vol. 31, no 1, p. 34-59Article in journal (Refereed)
    Abstract [en]

    This article considers tests for logistic smooth transition autoregressive (LSTAR) models accommodating multiple time dependent transitions between regimes when the data generating process is a random walk. The asymptotic null distributions of the tests, in contrast to the standard results in Lin and Teräsvirta (1994), are nonstandard. Monte Carlo experiments reveal that the tests have modest size distortions and satisfactory power against LSTAR models with multiple smooth breaks. The tests are applied to Swedish unemployment rates and the hysteresis hypothesis is over-turned in favour of an LSTAR model with two transitions between extreme regimes.

  • 66.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Strandberg, Rickard
    Dickey-Fuller type of tests against non-linear dynamic models2006In: Oxford Bulletin of Economics and Statistics, ISSN 0305-9049, E-ISSN 1468-0084, Vol. 68, no s1, p. 835-861Article in journal (Refereed)
    Abstract [en]

    In this paper, we introduce several test statistics testing the null hypothesis of a random walk (with or without drift) against models that accommodate a smooth nonlinear shift in the level, the dynamic structure and the trend. We derive analytical limiting distributions for all the tests. The power performance of the tests is compared with that of the unit-root tests by Phillips and Perron [Biometrika (1988), Vol. 75, pp. 335–346], and Leybourne, Newbold and Vougas [Journal of Time Series Analysis (1998), Vol. 19, pp. 83–97]. In the presence of a gradual change in the deterministics and in the dynamics, our tests are superior in terms of power.

  • 67.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Teräsvirta, Timo
    An extended constant conditional correlation GARCH model and its fourth-moment structure2004In: Econometric Theory, ISSN 0266-4666, E-ISSN 1469-4360, Vol. 20, no 5, p. 904-926Article in journal (Refereed)
    Abstract [en]

    The constant conditional correlation general autoregressive conditional heteroskedasticity (GARCH) model is among the most commonly applied multivariate GARCH models and serves as a benchmark against which other models can be compared. In this paper we consider an extension to this model and examine its fourth-moment structure. The extension, first defined by Jeantheau (1998, Econometric Theory 14, 70–86), is motivated by the result found and discussed in this paper that the squared observations from the extended model have a rich autocorrelation structure. This means that already the first-order model is capable of reproducing a whole variety of autocorrelation structures observed in financial return series. These autocorrelations are derived for the first- and the second-order constant conditional correlation GARCH model. The usefulness of the theoretical results of the paper is demonstrated by reconsidering an empirical example that appeared in the original paper on the constant conditional correlation GARCH model.

  • 68.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Teräsvirta, Timo
    Properties of moments of a family of GARCH processes1999In: Journal of Econometrics, ISSN 0304-4076, E-ISSN 1872-6895, Vol. 92, no 1, p. 173-192Article in journal (Refereed)
    Abstract [en]

    This paper considers the moments of a family of first-order GARCH processes. First, a general condition for the existence of any integer moment of the absolute values of the observations is given. Second, a general expression for this moment as a function of lower-order moments is derived. Third, the kurtosis and the autocorrelation function of the squared and absolute-valued observations are derived. The results apply to a number of different GARCH parameterizations. Finally, the existence, or lack thereof, of the theoretical counterpart to the so-called Taylor effect in some members of this GARCH family is discussed. Possibilities of extending the results to higher-order GARCH processes are indicated and potential applications of the statistical theory proposed.

  • 69.
    He, Changli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    Teräsvirta, Timo
    Gónzalez, Andrés
    Testing parameter constancy in stationary vector autoregressive models against continuous change2008In: Econometric Reviews, ISSN 0747-4938, E-ISSN 1532-4168, Vol. 28, no 1-3, p. 225-245Article in journal (Refereed)
    Abstract [en]

    In this article we derive a parameter constancy test of a stationary vector autoregressive model against the hypothesis that the parameters of the model change smoothly over time. A single structural break is contained in this alternative hypothesis as a special case. The test is a generalization of a single-equation test of a similar hypothesis proposed in the literature. An advantage here is that the asymptotic distribution theory is standard. The performance of the tests is compared to that of generalized Chow-tests and found satisfactory in terms of both size and power.

  • 70.
    Hjerpe, Olof
    Dalarna University, School of Education, Health and Social Studies, Mathematics Education.
    Feedback II: Hur feedback i form av feedbackfrågor påverkar elevers resonerande vid matematisk problemlösning2018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I den här kvalitativa studien undersöks hur elevers resonemang vid matematisk problemlösning påverkas av feedback given i form av frågor enligt en given modell. Elever i åk 7 har fått arbeta med ett matematiskt problem och i arbetet fått muntliga feedbackfrågor av olika bestämda typer som beskrivs närmare i §3.4. Studien visar hur lärares variation av feedbackfrågor kan påverka hur elever resonerar vid arbete med matematiska problem.

  • 71.
    Jia, Tao
    et al.
    Högskolan i Gävle.
    Jiang, Bin
    Högskolan i Gävle.
    Carling, Kenneth
    Dalarna University, School of Technology and Business Studies, Statistics.
    Bohlin, Magnus
    Dalarna University, School of Technology and Business Studies, Human Geography.
    Ban, Yifang
    KTH.
    An empirical study on human mobility and its agent-based modeling2012In: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, article id P11024Article in journal (Refereed)
    Abstract [en]

    This paper aims to analyze the GPS traces of 258 volunteers for a better understanding of both the human mobility patterns and the mechanism. We report the regular and scaling properties of human mobility from several aspects, and importantly we find its levy flight characteristic which is consistent with the previous studies. We further assume two factors that may govern the levy flight property: (1) the scaling and hierarchical properties of the purpose clusters which serve as the underlying spatial structure, and (2) the individual preferential behavior. To verify the assumptions, we implement an agent-based model with the two factors, and the simulated agents indeed reproduce the same levy flight pattern as the observed one. In order to enable the model to reproduce more mobility patterns, we add the model a third factor, the jumping factor which means the probability that one person may cancel the regular mobility schedule and visit a random place. With this factor, our model could cover a relatively wide range of human mobility patterns with exponent values from 1.55 to 2.05.

  • 72.
    Jonsson, Emma
    Dalarna University, School of Education, Health and Social Studies, Educational Work.
    Att utveckla elevers grundläggande begreppsförståelse i matematik: En litteraturstudie om hur matematikundervisningen i årskurs 1-3 kan utformas för att ge elever möjlighet att utveckla en god begreppsförståelse i matematik2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studier visar att svenska elevers resultat i matematik har försämrats och att en av de

    bakomliggande orsakerna till resultatnedgången är bristande begreppsförståelse.

    Samtidigt rapporteras det om att eleverna i undervisningen allt mer lämnas ensamma i

    sitt lärande i så kallat individuellt arbete. Tolkningen som kan göras är att det finns ett

    samband mellan elevers försämrade matematikkunskaper och undervisningen de

    möter i matematik. Syftet med denna studie är att få kunskap om hur

    matematikundervisningen kan utformas för att ge elever i årskurs 1-3 möjlighet att

    utveckla en god begreppsförståelse i matematik. Svaret söktes genom en systematisk

    litteraturstudie där litteratur och aktuell forskning söktes systematiskt. I studiens

    resultat exemplifieras en rad kommunikationsverktyg för läraren att använda direkt i

    undervisning, men också andra typer av verktyg, för att stödja och utveckla elevers

    förståelse för matematiska begrepp. Vidare synliggörs också fördelar med en lärare

    som möjliggör en undervisning där eleverna själva får kommunicera matematik och

    som agerar resurs för dem i deras övergång från det vardagliga till det matematiska

    språket. Kommunikation kan därför ses som ett viktigt verktyg i

    matematikundervisningen då det kommer till att utveckla elevers begreppsförståelse.

    Undervisningsmiljön behöver därför utformas till att passa en mer kommunikativ

    undervisning; en tillåtande miljö där eleverna tillåts och stöttas i att prata matematik.

  • 73.
    Jäder, Jonas
    et al.
    Dalarna University, School of Education, Health and Social Studies, Mathematics Education. Linköping University.
    Sidenvall, Johan
    Linköping University; School Administration, Municipality of Hudiksvall.
    Sumpter, Lovisa
    Department of Mathematics and Science Education, Stockholm University.
    Students’ Mathematical Reasoning and Beliefs in Non-routine Task Solving2016In: International Journal of Science and Mathematics Education, ISSN 1571-0068, E-ISSN 1573-1774, p. 1-18Article in journal (Refereed)
    Abstract [en]

    Beliefs and problem solving are connected and have been studied in different contexts. One of the common results of previous research is that students tend to prefer algorithmic approaches to mathematical tasks. This study explores Swedish upper secondary school students’ beliefs and reasoning when solving non-routine tasks. The results regarding the beliefs indicated by the students were found deductively and include expectations, motivational beliefs and security. When it comes to reasoning, a variety of approaches were found. Even though the tasks were designed to demand more than imitation of algorithms, students used this method and failed to solve the task. © 2016 Ministry of Science and Technology, Taiwan

  • 74.
    Laryea, Rueben
    et al.
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Carling, Kenneth
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Cialani, Catia
    Dalarna University, School of Technology and Business Studies, Economics.
    Nyberg, Roger G.
    Dalarna University, School of Technology and Business Studies, Information Systems.
    Sensitivity analysis of a risk classification model for food price volatility2018In: International Journal of Risk Assessment and Management, ISSN 1466-8297, E-ISSN 1741-5241, Vol. 21, no 4, p. 374-382Article in journal (Refereed)
    Abstract [en]

    A sensitivity analysis to vary the weights of an accurate predictive classification model to produce a mixed model for ranking countries on the risk of food price volatility is carried out in this paper. The classification model is a marginal utility function consisting of multiple criteria. The aim of the sensitivity analysis is to derive a mixed model to be used in ranking of country alternatives to aid in policy formulation. Since in real-life situations the data that goes into decision making could be subjected to possibilities of alterations over time, it is essential to aid decision makers to vary the weights of the criteria using both subjective and objective information to introduce imprecision and to generate relative values of the criteria with a scale to form a mixed model. The mixed model can be used to rank future relative alternative value data sets for policy formulation.

  • 75. Lee, Youngjo
    et al.
    Alam, Moudud
    Dalarna University, School of Technology and Business Studies, Statistics.
    Noh, M
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Skarin, Anna
    Analyzing spatially correlated counts with excessive zeros: a case of modeling the changes of reindeer distribution2013Report (Other academic)
  • 76. Lee, Youngjo
    et al.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Noh, Maengseok
    Data Analysis Using Hierarchical Generalized Linear Models with R2017Book (Other academic)
  • 77.
    Li, Dao
    Dalarna University, School of Technology and Business Studies, Statistics. Handelshögskolan vid Örebro universitet, Statistik.
    Common Features in Vector Nonlinear Time Series Models2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consists of four manuscripts in the area of nonlinear time series econometrics on topics of testing, modeling and forecasting nonlinear common features. The aim of this thesis is to develop new econometric contributions for hypothesis testing and forecasting in these area.

    Both stationary and nonstationary time series are concerned. A definition of common features is proposed in an appropriate way to each class. Based on the definition, a vector nonlinear time series model with common features is set up for testing for common features. The proposed models are available for forecasting as well after being well specified.

    The first paper addresses a testing procedure on nonstationary time series. A class of nonlinear cointegration, smooth-transition (ST) cointegration, is examined. The ST cointegration nests the previously developed linear and threshold cointegration. An Ftypetest for examining the ST cointegration is derived when stationary transition variables are imposed rather than nonstationary variables. Later ones drive the test standard, while the former ones make the test nonstandard. This has important implications for empirical work. It is crucial to distinguish between the cases with stationary and nonstationary transition variables so that the correct test can be used. The second and the fourth papers develop testing approaches for stationary time series. In particular, the vector ST autoregressive (VSTAR) model is extended to allow for common nonlinear features (CNFs). These two papers propose a modeling procedure and derive tests for the presence of CNFs. Including model specification using the testing contributions above, the third paper considers forecasting with vector nonlinear time series models and extends the procedures available for univariate nonlinear models. The VSTAR model with CNFs and the ST cointegration model in the previous papers are exemplified in detail,and thereafter illustrated within two corresponding macroeconomic data sets.

  • 78.
    Li, Dao
    Dalarna University, School of Technology and Business Studies, Statistics.
    Residual-based Inference for Common Nonlinear Features2013Report (Other academic)
    Abstract [en]

    This paper investigates common nonlinear features in multivariate nonlinear autore-gressive models via testing the estimated residuals. A Wald-type test is proposed and itis asymptotically Chi-squared distributed. Simulation studies are given to examine thefinite-sample properties of the proposed test.

  • 79.
    Li, Dao
    Dalarna University, School of Technology and Business Studies, Statistics.
    Testing linear cointegration against smooth-transition cointegration2011Report (Other academic)
    Abstract [en]

    This paper studies a smooth-transition (ST) type cointegration. The proposed ST cointegration allows for regime switching structure in a cointegrated system. It nests the linear cointegration developed by Engle and Granger (1987) and the threshold cointegration studied by Balke and Fomby (1997). We develop F-type tests to examine linear cointegration against ST cointegration in ST-type cointegrating regression models with or without time trends. The null asymptotic distributions of the tests are derived with stationary transition variables in ST cointegrating regression models. And it is shown that our tests have nonstandard limiting distributions expressed in terms of standard Brownian motion when regressors are pure random walks, while have standard asymptotic distributions when regressors contain random walks with nonzero drift. Finite-sample distributions of those tests are studied by Monto Carlo simulations. The small-sample performance of the tests states that our F-type tests have a better power when the system contains ST cointegration than when the system is linearly cointegrated. An empirical example for the purchasing power parity (PPP) data (monthly US dollar, Italy lira and dollar-lira exchange rate from 1973:01 to 1989:10) is illustrated by applying the testing procedures in this paper. It is found that there is no linear cointegration in the system, but there exits the ST-type cointegration in the PPP data.

  • 80.
    Li, Dao
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    He, Changli
    Dalarna University, School of Technology and Business Studies, Statistics.
    Forecasting with Vector Nonlinear Time Series Models2013Report (Other academic)
    Abstract [en]

    This work concerns forecasting with vector nonlinear time series models when errorsare correlated. Point forecasts are numerically obtained using bootstrap methods andillustrated by two examples. Evaluation concentrates on studying forecast equality andencompassing. Nonlinear impulse responses are further considered and graphically sum-marized by highest density region. Finally, two macroeconomic data sets are used toillustrate our work. The forecasts from linear or nonlinear model could contribute usefulinformation absent in the forecasts form the other model.

  • 81.
    Li, Dao
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    He, Changli
    Dalarna University, School of Technology and Business Studies, Statistics.
    Testing common nonlinear features in vector nonlinear autoregressive models2012Report (Other academic)
    Abstract [en]

    This paper studies a special class of vector smooth-transition autoregressive (VSTAR) models that contains common nonlinear features (CNFs), for which we proposed a triangular representation and developed a procedure of testing CNFs in a VSTAR model. We first test a unit root against a stable STAR process for each individual time series and then examine whether CNFs exist in the system by Lagrange Multiplier (LM) test if unit root is rejected in the first step. The LM test has standard Chi-squared asymptotic distribution. The critical values of our unit root tests and small-sample properties of the F form of our LM test are studied by Monte Carlo simulations. We illustrate how to test and model CNFs using the monthly growth of consumption and income data of United States (1985:1 to 2011:11).

  • 82.
    Lissollas, Mona
    Dalarna University, School of Education and Humanities, Educational Work.
    När närmiljö blir lärmiljö: Ett projekt om utomhusmatematik i årskurs 52012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med detta examensarbete har varit att genom lektioner, observationer, utvärderingar samt intervjuer med elever och lärare få en uppfattning om hur närmiljön vid skolan används idag i matematikundervisningen, hur den skulle kunna användas mera samt få en uppfattning av hur eleverna upplever utomhusundervisning i matematik och hur det påverkar elevernas lärande. Efter en litteraturstudie genomfördes ett projekt utomhus med matematiklektioner som handlade om geometri. Lektionerna bestod bland annat av att öva på geometriska former, skala, mäta med olika mätredskap, beräkna omkrets och area, uppskatta längder och använda gamla mätmetoder.

     

    Resultatet av projektet och intervjuerna visar att lärarna till viss del, mestadels sporadiskt, använder utemiljön i sin matematikundervisning speciellt tillsammans med de yngre barnen. Det finns en vilja bland lärare att använda närmiljön mer om tid kan frigöras till att få idéer, inspiration och planera övningar. En fördel som lärarna ser med matematikundervisning ute är att eleverna verkar komma ihåg och få en djupare kunskap för de moment som genomförts ute. Eleverna som deltagit i projektet med matematiklektioner i utemiljö uppfattar utomhusundervisning som något positivt och  flertalet upplever att de lär sig matematik bättre då de får vara ute och röra på sig samtidigt i friska luften. Det negativa var det kyliga vädret.

  • 83. Marjanovic, Jovana
    et al.
    Mulder, Han A
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics. SLU.
    Bijma, Piter
    Modelling the co-evolution of indirect genetic effects and inherited variability2018In: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 121, p. 631-647Article in journal (Refereed)
    Abstract [en]

    When individuals interact, their phenotypes may be affected not only by their own genes but also by genes in their social partners. This phenomenon is known as Indirect Genetic Effects (IGEs). In aquaculture species and some plants, however, competition not only affects trait levels of individuals, but also inflates variability of trait values among individuals. In the field of quantitative genetics, the variability of trait values has been studied as a quantitative trait in itself, and is often referred to as inherited variability. Such studies, however, consider only the genetic effect of the focal individual on trait variability and do not make a connection to competition. Although the observed phenotypic relationship between competition and variability suggests an underlying genetic relationship, the current quantitative genetic models of IGE and inherited variability do not allow for such a relationship. The lack of quantitative genetic models that connect IGEs to inherited variability limits our understanding of the potential of variability to respond to selection, both in nature and agriculture. Models of trait levels, for example, show that IGEs may considerably change heritable variation in trait values. Currently, we lack the tools to investigate whether this result extends to variability of trait values. Here we present a model that integrates IGEs and inherited variability. In this model, the target phenotype, say growth rate, is a function of the genetic and environmental effects of the focal individual and of the difference in trait value between the social partner and the focal individual, multiplied by a regression coefficient. The regression coefficient is a genetic trait, which is a measure of cooperation; a negative value indicates competition, a positive value cooperation, and an increasing value due to selection indicates the evolution of cooperation. In contrast to the existing quantitative genetic models, our model allows for co-evolution of IGEs and variability, as the regression coefficient can respond to selection. Our simulations show that the model results in increased variability of body weight with increasing competition. When competition decreases, i.e., cooperation evolves, variability becomes significantly smaller. Hence, our model facilitates quantitative genetic studies on the relationship between IGEs and inherited variability. Moreover, our findings suggest that we may have been overlooking an entire level of genetic variation in variability, the one due to IGEs.

  • 84.
    Meng, Xiangli
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Optimization heuristic solutions, how good can they be?: With empirical applications in location problems2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Combinatorial optimization problems, are one of the most important types of problems in operational research. Heuristic and metaheuristics algorithms are widely applied to find a good solution. However, a common problem is that these algorithms do not guarantee that the solution will coincide with the optimum and, hence, many solutions to real world OR-problems are afflicted with an uncertainty about the quality of the solution. The main aim of this thesis is to investigate the usability of statistical bounds to evaluate the quality of heuristic solutions applied to large combinatorial problems. The contributions of this thesis are both methodological and empirical. From a methodological point of view, the usefulness of statistical bounds on p-median problems is thoroughly investigated. The statistical bounds have good performance in providing informative quality assessment under appropriate parameter settings. Also, they outperform the commonly used Lagrangian bounds. It is demonstrated that the statistical bounds are shown to be comparable with the deterministic bounds in quadratic assignment problems. As to empirical research, environment pollution has become a worldwide problem, and transportation can cause a great amount of pollution. A new method for calculating and comparing the CO2-emissions of online and brick-and-mortar retailing is proposed. It leads to the conclusion that online retailing has significantly lesser CO2-emissions. Another problem is that the Swedish regional division is under revision and the border effect to public service accessibility is concerned of both residents and politicians. After analysis, it is shown that borders hinder the optimal location of public services and consequently the highest achievable economic and social utility may not be attained.

  • 85. Meng, Xiangli
    et al.
    Carling, Kenneth
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Rebreyend, Pascal
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    How do administrative borders affect accessibility to hospitals? The case of Sweden2018In: International Journal of Health Planning and Management, ISSN 0749-6753, E-ISSN 1099-1751, Vol. 33, no 3Article in journal (Refereed)
    Abstract [en]

    An administrative border might hinder the optimal allocation of a given set of resources by restricting the flow of goods, services, and people. In this paper, we address the question: Do administrative borders lead to poor accessibility to public service? In answering the question, we have examined the case of Sweden and its regional administrative borders and hospital accessibility. We have used detailed data on the Swedish road network, its hospitals, and its geo-coded population. We have assessed the population's spatial accessibility to Swedish hospitals by computing the inhabitants' distance to the nearest hospital. We have also elaborated several scenarios ranging from strongly confining regional borders to no confinements of borders and recomputed the accessibility. Our findings imply that administrative borders are only marginally worsening the accessibility.

  • 86.
    Meng, Xiangli
    et al.
    Dalarna University, School of Technology and Business Studies, Statistics.
    He, Changli
    Dalarna University, School of Technology and Business Studies, Statistics.
    Testing Seasonal Unit Roots in Data at Any Frequency, an HEGY approach2012Report (Other academic)
    Abstract [en]

    This paper generalizes the HEGY-type test to detect seasonal unit roots in data at any frequency, based on the seasonal unit root tests in univariate time series by Hylleberg, Engle, Granger and Yoo (1990). We introduce the seasonal unit roots at first, and then derive the mechanism of the HEGY-type test for data with any frequency. Thereafter we provide the asymptotic distributions of our test statistics when different test regressions are employed. We find that the F-statistics for testing conjugation unit roots have the same asymptotic distributions. Then we compute the finite-sample and asymptotic critical values for daily and hourly data by a Monte Carlo method. The power and size properties of our test for hourly data is investigated, and we find that including lag augmentations in auxiliary regression without lag elimination have the smallest size distortion and tests with seasonal dummies included in auxiliary regression have more power than the tests without seasonal dummies. At last we apply the our test to hourly wind power production data in Sweden and shows there are no seasonal unit roots in the series.

  • 87.
    Mihaescu, Oana
    et al.
    Dalarna University, School of Technology and Business Studies, Human Geography.
    vom Hofe, Rainer
    University of Cincinnati, School of Planning.
    Using Spatial Regression to Estimate Property Tax Discounts from Proximity to Brownfields: A Tool for Local Policy-Making2013In: Journal of Environmental Assessment Policy and Management, ISSN 1464-3332, E-ISSN 1757-5605, Vol. 15, no 1Article in journal (Refereed)
    Abstract [en]

    This paper assesses the discount in property values due to proximity to brownfields using a spatial hedonic price model. Using two Bayesian hedonic pricing models, namely the spatial lag of X (SLX) model and the spatial Durbin error model (SDEM), this study identifies a significant decrease in property values for properties located within 2,000 feet of a brownfield. The loss in property value and the subsequent decrease in tax revenue for the City of Cincinnati, Ohio, are then calculated based on these results. Using logarithmic transformations of the property value and the distance to the nearest brownfield variables, we calculate that a 1% increase in the average distance to the closest brownfield leads to a 0.0893% increase in market value. This translates into a $2,262,569 total annual revenue loss for the City of Cincinnati that could presumably be recovered following brownfield cleanup. In addition to accounting for the phenomenon of spatial dependence, this study contributes to the urban planning and environmental policy literature by providing a method for local policy-makers to identify and estimate the negative effects of brownfield sites on local tax revenue.

  • 88. Mischenko, Kateryna
    et al.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Holmgren, Sverker
    Mishchenko, Vladimir
    Assessing a multiple QTL search using the variance component model2010In: Computational biology and chemistry (Print), ISSN 1476-9271, E-ISSN 1476-928X, Vol. 34, no 1, p. 34-41Article in journal (Refereed)
    Abstract [en]

    Development of variance component algorithms in genetics has previously mainly focused on animal breeding models or problems in human genetics with a simple data structure. We study alternative methods for constrained likelihood maximization in quantitative trait loci (QTL) analysis for large complex pedigrees. We apply a forward selection scheme to include several QTL and interaction effects, as well as polygenic effects, with up to five variance components in the model. We show that the implemented active set and primal-dual schemes result in accurate solutions and that they are robust. In terms of computational speed, a comparison of two approaches for approximating the Hessian of the log-likelihood shows that the method using an average information matrix is the method of choice for the five-dimensional problem. The active set method, with the average information method for Hessian computation, exhibits the fastest convergence with an average of 20 iterations per tested position, where the change in variance components <0.0001 was used as convergence criterion.

  • 89.
    Mouresan, Elena Flavia
    et al.
    Swedish University of Agricultural Sciences.
    Selle, Maria
    Norwegian University of Science and Technology.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Genomic Prediction Including SNP-Specific Variance Predictors2019In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, article id g3.400381.2019Article in journal (Refereed)
    Abstract [en]

    The increasing amount of available biological information on the markers can be used to inform the models applied for genomic selection to improve predictions. The objective of this study was to propose a general model for genomic selection using a link function approach within the hierarchical generalized linear model framework (hglm) that can include external information on the markers. These models can be fitted using the well-established hglm package in R. We also present an R package (CodataGS) to fit these models, which is significantly faster than the hglm package. Simulated data was used to validate the proposed model. We tested categorical, continuous and combination models where the external information on the markers was related to 1) the location of the QTLs on the genome with varying degree of uncertainty, 2) the relationship of the markers with the QTLs calculated as the LD between them, and 3) a combination of both. The proposed models showed improved accuracies from 3.8% up to 23.2% compared to the SNP-BLUP method in a simulated population derived from a base population with 100 individuals. Moreover, the proposed categorical model was tested on a dairy cattle dataset for two traits (Milk Yield and Fat Percentage). These results also showed improved accuracy compared to SNP-BLUP, especially for the Fat% trait. The performance of the proposed models depended on the genetic architecture of the trait, as traits that deviate from the infinitesimal model benefited more from the external information. Also, the gain in accuracy depended on the degree of uncertainty of the external information provided to the model. The usefulness of these type of models is expected to increase with time as more accurate information on the markers becomes available.

  • 90.
    Mårtensson, Jelena
    Dalarna University, School of Education, Health and Social Studies, Educational Work.
    Förståelse av sambandet mellan addition och subtraktion: En litteraturstudie om hur förståelsen av sambandet mellan addition och subtraktion i årskurs 1-3 påverkar elevers kunskaper inom subtraktion2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att undersöka hur en förståelse av sambandet mellan addition och subtraktion kan påverka elevers kunskaper inom subtraktion. Syftet konkretiseras genom följande frågeställning: Vilken betydelse har sambandet mellan addition och subtraktion för elevers kunskaper inom subtraktion i årskurs 1-3? Frågeställningen har besvarats med hjälp av en systematisk litteraturstudie där vetenskapliga artiklar har sökts, analyserats och kritiskt granskats. Resultatet av studien visar att kunskap och förståelse av den inversa operationen hjälper elever att förstå och lösa andra problem inom subtraktion. En förståelse av den inversa operationen förefaller krävas för att förstå och använda sig av uppdelning i termer. Elever använder deras kunskap om sambandet mellan addition och subtraktion för att lösa uppgifter bland annat genom att omvandla uppgifter så att de kan lösas med hjälp av den inversa operationen. Resultatet visar även att det verkar finnas olika faktorer, exempelvis beräkningsfärdigheter, som påverkar elevernas resultat vid användning av den inversa operationen.

  • 91. Nassif, Nabil R.
    et al.
    Fayyad, Dolly
    Cortas Nordlander, Maria
    Lebanese University, Beirut, Lebanon.
    Sliced-Time Computations with Re-scaling for Blowing-Up Solutions to Initial Value Differential Equations2005In: Computational Science – ICCS 2005 / [ed] Sunderam, Vaidy S.; van Albada, Geert Dick; Sloot, Peter M. A.; Dongarra, Jack J., Springer Berlin/Heidelberg, 2005, p. 58-65Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a new approach to simulate time-dependent initial value differential equations which solutions have a common property of blowing-up in a finite time. For that purpose, we introduce the concept of “sliced-time computations”, whereby, a sequence of time intervals (slices) {[Tn − 1, Tn]| n ≥ 1} is defined on the basis of a change of variables (re-scaling), allowing the generation of computational models that share symbolically or numerically “similarity” criteria. One of these properties is to impose that the re-scaled solution computed on each slice do not exceed a well-defined cut-off value (or threshold) S. In this work we provide fundamental elements of the method, illustrated on a scalar ordinary differential equation y′ = f(y) where f(y) verifies $\int_0^\infty {f(y)dy} < \infty$. Numerical results on various ordinary and partial differential equations are available in [7], some of which will be presented in this paper.

  • 92. Nassif, Nabil R.
    et al.
    Fayyad, Dolly
    Cortas Nordlander, Maria
    Lebanese University, Beirut, Lebanon.
    Sliced-Time Computations with Re-scaling for Blowing-Up Solutions to Initial Value Differential Equations2005Conference paper (Refereed)
  • 93. Nelson, Ronald M
    et al.
    Temnykh, Svetlana V
    Johnson, Jennifer L
    Kharlamova, Anastasiya V
    Vladimirova, Anastasiya V
    Shepeleva, Darya V
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Trut, Lyudmila N
    Carlborg, Örjan
    Kukekova, Anna V
    Genetics of interactive behavior in silver foxes (Vulpes vulpes)2017In: Behavior Genetics, ISSN 0001-8244, E-ISSN 1573-3297, Vol. 47, no 1, p. 88-101Article in journal (Refereed)
    Abstract [en]

    Individuals involved in a social interaction exhibit different behavioral traits that, in combination, form the individual's behavioral responses. Selectively bred strains of silver foxes (Vulpes vulpes) demonstrate markedly different behaviors in their response to humans. To identify the genetic basis of these behavioral differences we constructed a large F2 population including 537 individuals by cross-breeding tame and aggressive fox strains. 98 fox behavioral traits were recorded during social interaction with a human experimenter in a standard four-step test. Patterns of fox behaviors during the test were evaluated using principal component (PC) analysis. Genetic mapping identified eight unique significant and suggestive QTL. Mapping results for the PC phenotypes from different test steps showed little overlap suggesting that different QTL are involved in regulation of behaviors exhibited in different behavioral contexts. Many individual behavioral traits mapped to the same genomic regions as PC phenotypes. This provides additional information about specific behaviors regulated by these loci. Further, three pairs of epistatic loci were also identified for PC phenotypes suggesting more complex genetic architecture of the behavioral differences between the two strains than what has previously been observed.

  • 94.
    Nelson, Ronald Michael
    et al.
    Swedish University of Agricultural Sciences.
    Nettelblad, Carl
    Uppsala University.
    Pettersson, Mats E
    Swedish University of Agricultural Sciences.
    Shen, Xia
    Swedish University of Agricultural Sciences; Uppsala University;.
    Crooks, Lucy
    Swedish University of Agricultural Sciences.
    Besnier, Francois
    Swedish University of Agricultural Sciences.
    Alvarez-Castro, José
    Swedish University of Agricultural Sciences.
    Rönnegård, Lars
    Dalarna University, School of Technology and Business Studies, Statistics.
    Ek, Weronica
    Swedish University of Agricultural Sciences.
    Carlborg, Örjan
    Swedish University of Agricultural Sciences.
    MAPfastR: quantitative trait loci mapping in outbred line crosses2013In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, Vol. 12, no 3, p. 2147-2149Article in journal (Refereed)
    Abstract [en]

    MAPfastR is a software package developed to analyze QTL data from inbred and outbred line-crosses. The package includes a number of modules for fast and accurate QTL analyses. It has been developed in the R language for fast and comprehensive analyses of large datasets. MAPfastR is freely available at: http://www.computationalgenetics.se/?page_id=7.

  • 95.
    Niskanen, Virpi
    Dalarna University, School of Education and Humanities, Educational Work.
    Att utveckla barns matematiklärande i förskolan: En fallstudie om pedagogers arbete med matematik för barn i åldern 4-5 år2012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att synliggöra pedagogernas arbete med matematik i förskolans inomhusmiljö med barn i åldern 4 - 5 år. Utgångspunkt för synliggörande är Lpfö 98/10 mål och uttrycksformer i matematik. Förhoppningen är att resultatet från undersökningen kan ligga till grund för att utveckla verksamheten. För att nå syftet har följande frågeställningar använts:1. Hur arbetar pedagogerna med barns matematiklärande? Vilket matematikinnehåll? Vilka uttrycksformer?2. I vilka situationer sker pedagogers arbete med matematik? I vilka av de sex vardagssituationerna: barns lek med närvarande pedagog, samling, utgång, ingång, lunch och läsvila?3. Hur ser de verksamma pedagogerna på behov, möjligheter och hinder för att utveckla arbetet med barns matematiklärande?För att få svar på frågeställning 1 och 2 genomfördes strukturerade observationer med hjälp av observationsscheman. Sammanlagt observerades fem avdelningar och på varje avdelning observerades samtliga sex situationer, det vill säga vid 30 tillfällen. Barnen var i åldern 4-5 år och med pedagog menas i undersökningen all personal som arbetade på avdelningarna. För att få svar på den tredje och sista frågeställningen genomfördes kvalitativa intervjuer genom fokusgruppssamtal vilket innebär att samtalet utfördes avdelningsvis med samma fem avdelningar vilka ingick i observationerna.Resultatet visar att pedagoger arbetar med barns matematiklärande i större utsträckning än de själva tror och upplever. Observationerna åskådliggör att de matematiska aktiviteterna räkna och förklara förekommer oftast, följt av lokalisera, mäta och konstruera. Den matematiska aktiviteten leka förekommer sällan. Av de sex undersökta uttrycksformerna dominerar samtal, följt av rörelse, lek/drama, sång/musik, bild/form och dans. Pedagogerna har en önskan om fortbildning i matematik, så att de kan synliggöra matematiklärandet för sig själva, barnen och hela verksamheten. Av resultatet framgår att de matematiska strävansmålen i läroplanen för förskolan inte är helt tydliga för personalen, och att uttrycksformerna inte används fullt ut av pedagogerna i det dagliga arbetet.En slutsats av undersökningens resultat är att pedagogerna behöver ökad kunskap i arbetet med barns matematiklärande samt stöd för att förtydliga och omsätta de olika matematiska strävansmålen i läroplanen för förskolan i verksamheten.

  • 96.
    Nordlander, Edvard
    et al.
    Högskolan i Gävle, Elektronik.
    Cortas Nordlander, Maria
    Vasaskolan, Gävle, Sverige.
    Enkla regler för en komplex värld2016In: Ämnesdidaktiska utmaningar - inom matematik, naturvetenskap och teknik / [ed] Mikael Björling, Gävle: Gävle University Press , 2016, 1, p. 27-46Chapter in book (Other academic)
  • 97.
    Nordlander, Edvard
    et al.
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Cortas Nordlander, Maria
    Vasaskolan, Gävle.
    Konsten att berätta en god historiaManuscript (preprint) (Other (popular science, discussion, etc.))
    Abstract [sv]

    Problemlösning uppfattas av många elever som en svårighet att övervinna genom att försöka lära sig utantill. Detta synsätt betecknar en algoritmisk inställning till lärande och har egentligen mycket lite med problemlösning att göra. Man sätter sin tillit till att upprepning av recept ger lika gott resultat oavsett problemställning. Vissa tycker dessutom att ett felaktigt resonemang, eller ett resonemang med bristfälliga eller obefintliga motiveringar, kan anses vara acceptabelt så länge svaret är korrekt.

    För att förebygga en algoritmisk inställning till problemlösning kan man införa en strategi för att förbättra problemlösningsförmågan hos elever – en metod som alla elever kan ta till sig. Att systematiskt teckna uppgiften är detsamma som att metodiskt reda ut för sig själv vad uppgiften går ut på, vilka teoretiska resonemang man kan tillämpa, hur man kan tänkas lösa uppgiften grundat på dessa teoretiska resonemang, samt slutligen genomföra lösningen på ett tydligt sätt. En god idé är att tänka sig att någon annan skall kunna följa resonemanget utan några andra hjälpmedel än den beskrivning som eleven själv producerar.

    De flesta brukar fascineras av en god historia. Det gäller för pedagogen att fånga intresset genom att framställa sin kunskap i berättandets form på ett begripligt, metodiskt uppbyggt och trovärdigt sätt. Även matematisk eller tillämpad problemlösning kan beskrivas för elever på detta vis p.g.a. sin logiska uppbyggnad.

    Man kan indela en god historia i fyra oundgängliga punkter: ingress, intrig, uppbyggnad av spänning och, slutligen, upplösning. Härutöver kan man tillägga ytterligare två punkter för att förgylla berättandet, nämligen prolog och epilog.

  • 98.
    Nyberg, Roger G.
    et al.
    Dalarna University, School of Technology and Business Studies, Information Systems.
    Yella, Siril
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    Gupta, Narendra K.
    Edinburgh Napier University.
    Dougherty, Mark
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    Inter-rater reliability in determining the types of vegetation on railway trackbeds2015In: Web Information Systems Engineering – WISE 2015: 16th International Conference, Miami, FL, USA, November 1-3, 2015, Proceedings, Part II / [ed] Wang, J., Cellary, W., Wang, D., Wang, H., Chen, S.-C., Li, T., Zhang, Y., Springer, 2015, Vol. 9419, p. 379-390Conference paper (Refereed)
    Abstract [en]

    Vegetation growing on railway trackbeds and embankments can present several potential problems. Consequently, such vegetation iscontrolled through various maintenance procedures. In order to investigate the extent of maintenance needed, one of the first steps in anymaintenance procedure is to monitor or inspect the railway section in question. Monitoring is often carried out manually by sending out inspectorsor by watching recorded video clips of the section in question.To facilitate maintenance planning, the ability to assess the extent of vegetation becomes important. This paper investigates the reliability ofhuman assessments of vegetation on railway trackbeds.In this study, five maintenance engineers made independent visual estimates of vegetation cover and counted the number of plant clusters fromimages.The test results showed an inconsistency between the raters when it came to visually estimating plant cover and counting plant clusters. The resultsshowed that caution should be exercised when interpreting individual raters’ assessments of vegetation.

  • 99.
    Onwuka, Kajsa
    Dalarna University, School of Education, Health and Social Studies, Educational Work.
    Matematisk problemlösning i grupp: En litteraturstudie om genomförande av undervisning med matematisk problemlösning i grupp2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det har visat sig att svenska elever presterar sämre än genomsnittet av OECD länderna

    gällande problemlösning i matematik enligt den senaste PISA undersökningen. Det har också

    visat sig att elever arbetar mycket individuellt vilket kan vara en orsak till sjunkande resultat i

    skolan. Syftet med denna studie är därför att genom tidigare forskning få kunskap om hur

    lärare arbetar med matematisk problemlösning i grupp. Med frågeställningen: På vilket sätt

    kan matematisk problemlösning i grupp genomföras för att gynna lärandet? För att besvara

    studiens frågeställning har en systematisk litteraturstudie genomförts där svaret på

    frågeställningen besvarats utifrån aktuell forskning. Resultatet för denna studie visar på hur

    viktigt det är att läraren noggrant planerar sina lektioner. Läraren bör välja uppgifter med

    omsorg och vara väl insatt i problemen samt följa en strukturerad undervisning för att kunna

    bemöta och stötta sina elever. Vidare konstateras att klassrumsmiljön och ett tillåtande klimat

    är viktigt för att diskussioner och samtal ska äga rum vilket är en central del i arbetet med

    problemlösning i grupp som skapar större förståelse för matematik och ökar

    kommunikationsförmågan. Resultatet visar på att problemlösning i grupp kräver en engagerad

    lärare som planerar och styr undervisningen med eleverna i fokus och där elevernas egna

    strategier och metoder belys och synliggörs.

  • 100.
    Petersén Hammarsten, Elin
    Dalarna University, School of Education and Humanities, Educational Work.
    Matematikläxans fördelar och nackdelar: En intervjustudie av lärares syn på matematikläxor i grundskolans tidigare år2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to gain insight into teachers’ views of mathematics lessons in primary school. The hope is to gain understanding of teachers’ aim with mathematic homework and what skills students are expected to develop with help of mathematic homework as well as comparing the advantages and disadvantages that mathematic homework has. To investigate this, the seven interviews have been conducted with teachers from different schools and different grades from 1-6. All the teachers interviewed teach mathematics. Teachers’ experience of the importance of homework is an important area to gain knowledge of why was this investigation. The teachers who participated in the interviews expressed different views on mathematic homework. Something teachers agreed on was that homework is a school assignment that students bring home after school and working on at home. The teachers also expressed unanimously that the students do not develop any abilities with mathematic homework help but that pupils develop abilities in school with help of the teachers. It appeared that all teachers felt that mathematics homework was time consuming and for mathematics homework to achieve its purpose in the best possible way more time was needed. Also to link with teaching and follow-upare two key elements for the purpose of mathematic homework to be achieved. The results show that some teachers have negative attitudes toward mathematic homework tracking and coupling is not present and therefore loses mathematic lesson's purpose. Parents circumstances are very different. It may be that they have problems with the Swedish language or not are involved in the child's schooling. Other teachers have a positive attitude towards mathematic homework because proficiency training and rehearsal is important and the time needed for this is not enough in school.

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