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  • 251.
    Lindström, Fredrik
    et al.
    Försäkringskassan.
    Holgersson, Thomas
    Jönköping University, Jönköping International Business School, JIBS, Economics.
    Forecast mean squared error reductionin the VAR(1) process2009In: Journal of Applied Statistics, ISSN 0266-4763, E-ISSN 1360-0532, Vol. 36, no 12, p. 1369-1384Article in journal (Refereed)
  • 252.
    Linusson, Henrik
    et al.
    Högskolan i Borås, Institutionen Handels- och IT-högskolan.
    Johansson, Ulf
    Högskolan i Borås, Institutionen Handels- och IT-högskolan.
    Löfström, Tuve
    Högskolan i Borås, Institutionen Handels- och IT-högskolan.
    Signed-Error Conformal Regression2014In: Advances in Knowledge Discovery and Data Mining 18th Pacific-Asia Conference, PAKDD 2014 Tainan, Taiwan, May 13-16, 2014 Proceedings, Part I, Springer, 2014, p. 224-236Conference paper (Refereed)
    Abstract [en]

    This paper suggests a modification of the Conformal Prediction framework for regression that will strengthen the associated guarantee of validity. We motivate the need for this modification and argue that our conformal regressors are more closely tied to the actual error distribution of the underlying model, thus allowing for more natural interpretations of the prediction intervals. In the experimentation, we provide an empirical comparison of our conformal regressors to traditional conformal regressors and show that the proposed modification results in more robust two-tailed predictions, and more efficient one-tailed predictions.

  • 253.
    Lundin, Rolf A.
    Jönköping University, Jönköping International Business School, JIBS, Media, Management and Transformation Centre (MMTC).
    Metodproblem vid simulering1972Book (Other academic)
  • 254.
    Lübking, Amanda
    Jönköping University, School of Education and Communication.
    Matematiklärares val av huvudräkningsstrategier inom addition: En intervjustudie av 6 lärare i Sverige och England2016Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The study is based on a qualitatively directed method and the main aim is to investigate, and examine the mental arithmetic strategies of both Swedish and English teachers. In particular, the methods they use, to teach addition. The empirical data within this research is based on first hand interviews with six teachers; three from Sweden, and three from England. The study is inspired by a Hermeneutic Perspective in combination with Grounded Theory. The word hermeneutic, means that all of the data contained in the study has been interpreted and analyzed by the researcher. Grounded Theory is a common method used to analyze qualitative data. With this theory, categories have been created on the basis of the results obtained within this study. The results of the study show that Swedish teachers' most common choices of strategies are; partitioning method, and algorithms. In contrast, the English teachers’ strategies are the following; number bonds, the additiontable and algorithms. The results of this study also illustrate the differences between the Swedish and the English teachers’ choices of strategies.

  • 255.
    Mahmood, Y.
    et al.
    Institut für Theoretische Informatik, Leibniz Universität Hannover, Hanover, Germany.
    Meier, A.
    Institut für Theoretische Informatik, Leibniz Universität Hannover, Hanover, Germany.
    Schmidt, Johannes
    Jönköping University, School of Engineering, JTH, Computer Science and Informatics.
    Parameterised Complexity of Abduction in Schaefer’s Framework2020In: Logical Foundations of Computer Science: International Symposium, LFCS 2020, Deerfield Beach, FL, USA, January 4–7, 2020 Proceedings / [ed] Artemov S., Nerode A., Cham: Springer, 2020, p. 195-213Conference paper (Refereed)
    Abstract [en]

    Abductive reasoning is a non-monotonic formalism stemming from the work of Peirce. It describes the process of deriving the most plausible explanations of known facts. Considering the positive version asking for sets of variables as explanations, we study, besides asking for existence of the set of explanations, two explanation size limited variants of this reasoning problem (less than or equal to, and equal to). In this paper, we present a thorough two-dimensional classification of these problems. The first dimension is regarding the parameterised complexity under a wealth of different parameterisations. The second dimension spans through all possible Boolean fragments of these problems in Schaefer’s constraint satisfaction framework with co-clones (STOC 1978). Thereby, we almost complete the parameterised picture started by Fellows et al. (AAAI 2012), partially building on results of Nordh and Zanuttini (Artif. Intell. 2008). In this process, we outline a fine-grained analysis of the inherent parameterised intractability of these problems and pinpoint their FPT parts. As the standard algebraic approach is not applicable to our problems, we develop an alternative method that makes the algebraic tools partially available again.

  • 256.
    Mahmoudi, Akram
    et al.
    Department of Statistics, University of Tabriz, Tabriz, Iran.
    Arabi Belaghi, Reza
    Department of Statistics, University of Tabriz, Tabriz, Iran.
    Shrinkage Estimators in Gamma Regression Model2018Conference paper (Refereed)
  • 257.
    Malmqvist, Maria
    Jönköping University, School of Education and Communication.
    Digitala eller analoga läromedel i matematik: En fenomenografisk studie om högstadieelevers uppfattningar av digitala läromedel jämfört med analoga i matematik2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The digitizing in Swedish school is a process in progress for many years and since the autumn term of 2017 there are new writings in the curriculum about strengthened digital competence (Skolverket 2017). Municipalities invest in giving every pupil a digital aid such as a laptop or a tablet. At the time, no clear connection between these invests and higher goal achievement have been proved. There are only a few studies about pupils´ perceptions of digitizing in school which prompted this study with purpose to investigate and describe secondary school pupils’ own perceptions of digital teaching materials compared to analogue in mathematics and thereby contribute to in-depth knowledge. Three research questions were formulated to fulfill the purpose: How do pupils work with digital teaching materials compared to analogue teaching materials in mathematics? What aspects of learning do pupils distinguish in relation to digital teaching materials compared to analogue teaching materials? Do pupils prefer digital teaching materials, analogue teaching materials or a combination? Since the purpose of the study is to search and describe the pupils’ perceptions of a phenomenon the choice has been made to use a phenomenographical approach and this qualitative method has also been used in gathering and analyzing data. To answer the research questions the material gathering consists of 11 recorded and transcribed interviews with secondary school pupils. The material has been analyzed and resulted in three different outcomes with description categories linked to each research question. Together, the questions outcomes constitute the result of the study (Marton & Booth, 2000; Uljens, 1989). The result also shows that pupils are not undivided positive to digital teaching materials in mathematics and prefer a combination of digital and analogue teaching materials. They describe motivation and variation as a basis for their positioning. The pupils want to be involved in decision making concerning when and how digital and analogue teaching materials should be used to be helpful in work and learning in mathematics. The Swedish school stands in front of a changed view of knowledge and learning since digitizing where the traditional view of knowledge should be challenged in order to reach an increased goal achievement (Kjällander 2014; Kroksmark et al. 2013; Steinberg 2013). In this change process the pupils should, based on an interpretation of their perceptions in the study, be involved.

  • 258.
    Mandal, Saumen
    et al.
    Department of Statistics, University of Manitoba, Winnipeg, Canada.
    Arabi Belaghi, Reza
    Department of Statistics, University of Tabriz, Tabriz, Iran.
    Mahmoudi, Akram
    Department of Statistics, University of Tabriz, Tabriz, Iran.
    Aminnejad, Minoo
    Department of Statistics, Razi University, Kermanshah, Iran.
    Stein-type shrinkage estimators in gamma regression model with application to prostate cancer data2019In: Statistics in Medicine, ISSN 0277-6715, E-ISSN 1097-0258, Vol. 38, no 22, p. 4310-4322Article in journal (Refereed)
    Abstract [en]

    Gamma regression is applied in several areas such as life testing, forecasting cancer incidences, genomics, rainfall prediction, experimental designs, and quality control. Gamma regression models allow for a monotone and no constant hazard in survival models. Owing to the broad applicability of gamma regression, we propose some novel and improved methods to estimate the coefficients of gamma regression model. We combine the unrestricted maximum likelihood (ML) estimators and the estimators that are restricted by linear hypothesis, and we present Stein-type shrinkage estimators (SEs). We then develop an asymptotic theory for SEs and obtain their asymptotic quadratic risks. In addition, we conduct Monte Carlo simulations to study the performance of the estimators in terms of their simulated relative efficiencies. It is evident from our studies that the proposed SEs outperform the usual ML estimators. Furthermore, some tabular and graphical representations are given as proofs of our assertions. This study is finally ended by appraising the performance of our estimators for a real prostate cancer data. 

  • 259.
    Meijer, Simon
    Jönköping University, School of Education and Communication.
    Huvudräkningsstrategier inom addition och subtraktion: bland elever i årskurs sex2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During my practical training periods I became interested in mental arithmetic because I expe­rienced that the students chose calculators despite their knowledge of mental arithmetic strat­egies. According to skolverket (2011b) students shall take part of different strategies to strengthen their selfconfidence and belief in their own ability. The purpose of this study was to identify which strategies some students in middle school choose when they are practising mental arithmetic in addition and subtraction. The study was based on a qualitative method and hermeneutic as a theoretical approach. The sample consisted of a targeted selection in combination with a convenience selection and resulted in three students from each of three different schools and school areas. Mental arithmetic tasks and interviews were used as data collection method. Data processing of the interviews has been processed using hermeneutics method and is based on interpretation. The result of the study showed that partitioning num­bers, algorithm and double was the most common mental arithmetic strategies in addition. When it comes to strategies in subtraction the students varied more and the most common was counting upwards, algorithm, compare, partitioning numbers, complementary addition and counting back from. The result also showed that there was no significant difference between the schools except school II and III when it comes to the strategy counting upwards. The dif­ference was that school II uses several different strategies when performing subtractions. It was rather clear that the students in this study had a good knowledge of various mental arithmetic strategies for addition and subtraction, and according to themselves it was a consequence of the various strategies in mental arithmetics, that their teachers had taught them.

  • 260.
    Mellroth, Elisabet
    et al.
    Karlstad University, Department of Mathematics and Computer Science, Sweden.
    Boesen, Jesper
    Jönköping University, School of Education and Communication, HLK, Praktiknära utbildningsforskning (PUF), Mathematics Education Research.
    Noticing mathematical potential – A proposal for guiding teachers2019In: Proceedings of the Eleventh Congress of the European Society for Research in Mathematics Education / [ed] Uffe Thomas Jankvist, Marja van den Heuvel-Panhuizen & Michiel Veldhuis, European Society for Research in Mathematics Education, 2019, p. 3688-3695Conference paper (Refereed)
    Abstract [en]

    It has been shown to be problematic for teachers to use Krutetskii´s definition of mathematical abilities to recognize mathematically highly able pupils (MHAPs). Aiming to concretize what teachers can notice in pupils’ problem-solving processes, we connect a 10-year-old boy’s problemsolving process to some of the abilities defined by Krutetskii. The results give clear descriptions of what teachers can observe in pupils’ mathematical activities to notice their mathematical potential. We concretize, for example, how a pupil’s abilities to grasp a problem’s formal structure and to generalize can be observed. To be able to notice MHAPs, teachers need research-based support on how and what to observe in their pupils. Our proposed guide needs to be tested and validated to explore if it will help teachers to notice MHAPs s and subsequently support their learning.

  • 261.
    Michels Hjort, Natalie
    Jönköping University, School of Education and Communication, HLK, School Based Research, Mathematics Education Research.
    Prov och kognitiv uthållighet: En studie av provutformning2011Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Alla har en uppfattning om hur ett matematikprov ska se ut, något som ärvts ner genom generationer. Men är utformningen verkligen optimal för att eleverna ska kunna prestera enligt sin förmåga? Studier av kognitiv kapacitet har visat att kognitivt krävande uppgifter frestar på arbetsminnet och skapar störande effekter som sänker hjärnans prestationsförmåga. Således är kanske den traditionella provutformningen med de svåra uppgifterna sist inte optimal för att eleverna ska kunna visa sina kunskaper på ett sätt som gör dem rättvisa.

    Denna kvantitativa studies syfte var att undersöka om provfrågornas ordning påverkar elevernas prestationer vid utförandet av matematikprov. Vidare var även av intresse om utformningen påverkade elevernas motivationsnivå, åsikt om provet eller hur lång tid det tog för dem att slutföra alla uppgifter. Två olika provutformningar undersöktes – en med de svåra uppgifterna sist och en med omvänd ordning.

    Studiens resultat visade ingen stark korrelation mellan utformningen och hur eleverna presterat i allmänhet. Den visade dock att utformningen med de svårare uppgifterna först möjligen kunde gynna de mest ambitiösa eleverna som satt med provet länge. Dessa elever tenderade att prestera bättre och de utförde provet under kortare tid än eleverna i kontrollgruppen. Tidsåtgången i allmänhet påverkades dock inte och inte heller elevernas motivationsnivå. Studien visade slutligen ett starkt samband mellan elevernas åsikt och utformningen: de tenderade att vara mer osäkra i sina åsikter om den nya utformningen och var mer positivt inställda till utformningen med de svåra uppgifterna sist.

  • 262.
    Moensjö, Rebecca
    et al.
    Jönköping University, School of Education and Communication.
    Pana, Daniela
    Jönköping University, School of Education and Communication.
    Matematik i förskoleklassen: Lärares didaktiska val med fokus på vad och hur, samt grunder för deras val2015Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to contribute to knowledge about which mathematical activities occur in the preschool classes, and how this appears in relation to previous research on what can be considered as a good basis in preschool, for the childrens future mathematical development. This purpose will be met by answering the questions: what mathematical contents do the teachers choose to work the most with in preschool, how do the teachers in preschool primarily choose to convey the mathematical content and which are the different grounds that the teachers’ choices of mathematical contents and methods are based on

    Our study is based on an earlier one, in which both national and international researches were reviewed. Both the previous study and our empirical investigation rest on the desire to get an idea of ​​what can be considered as a good basis for children's future mathematical development. In our empirical study we assume a positivistic view of knowledge, hence we used the quantitative method to collect data. We wanted to be able to draw logical conclusions from the facts revealed by the collected and analyzed data we received. The sample of respondents was limited to active preschool teachers from four small municipalities in Sweden. The data was collected using surveys. The number of respondents who participated in the survey was 41. The analysis of the results showed that the majority of the respondents primarily chose to work with mathematical contents included in the areas of numbers and their usage. When it comes to mathematical operations, the areas that were used more often by the respondents were the understanding of numbers and their usage, geometry, and problem solving. Thus, algebra, probability and statistics, as well as associations and conversions were used less frequently. Regarding the results concerning the selection of methods to convey the mathematical contents, the analysis showed that most respondents primarily use teacher led activities. Many also use games and capture the mathematics of everyday life. A smaller number of respondents makes use of group activities and teaching materials. Most respondents stated that they based their mathematical activities on the mathematics curriculum and their own experience. Not as many respondents indicated that they supported their business on proven experience or research. Some respondents also indicated that they supported their mathematical operations on the teaching materials they use. 

    The conclusion drawn from this empirical study is that the mathematical operations and activities conducted in preschools today vary between different preschools. Nevertheless it appears that children in many of these preschool classes have a relatively good basis for their future mathematical education. However, they may not get an equivalent basis for the primary school mathematical learning.

  • 263.
    Moscati, Annika
    Sapienza University of Rome.
    La pratica della prospettiva – gli strumenti per costruire la prospettiva2012In: Attualità della geometria descrittiva / [ed] Laura Carlevaris, Laura De Carlo, Riccardo Migliari, Rome: Gangemi , 2012, p. 457-466Chapter in book (Other academic)
  • 264. Murtaza, S.
    et al.
    Sattar, A.
    Ahmed, N.
    Ijaz, M.
    Shahzad, M.
    Omer, Talha
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Outcomes of exogenous oxytocin administration on pregnancy rate, embryonic and foetal losses in Nili-Ravi buffalo2019Conference paper (Refereed)
  • 265.
    Mutshinda, Crispin M.
    et al.
    University of Helsinki, Finland.
    Antai, Imoh
    Department of Marketing, Supply Chain Management and Corporate Geography, Swedish School of Economics and Business Administration, Hanken, Helsinki, Finland.
    O'Hara, Robert B.
    University of Helsinki, Finland.
    A probabilistic approach to exposure risk assessment2008In: Stochastic environmental research and risk assessment (Print), ISSN 1436-3240, E-ISSN 1436-3259, Vol. 22, no 4, p. 441-449Article in journal (Refereed)
    Abstract [en]

    The introduction of hazardous substances into the environment has long been recognized as being a cause of several diseases in humans, wildlife, and plants. The damaging character of suspected contaminants is usually assessed via a "reject/retain" design with no explicit link between levels of exposure and intensities of the potential adverse health effects even though this connection may be important for the development of public health regulations that limit exposure to hazardous substances. Here, we propose a probabilistic approach to exposure risk assessment as a way around this typical flaw. We develop a Bayesian model using proximity to the source of an alleged contaminant as a surrogate for exposure. Subsequently, we carry out an experimental study based on simulated data to illustrate the model implementation with real world data. We also discuss a possible way of extending the model to accommodate potential heterogeneity in the spatial distribution of the focal disease.

  • 266.
    Myrta, Zelfi
    Jönköping University, School of Education and Communication.
    Lärares uppfattningar av IKT: En studie om lärares uppfattningar av IKT i matematikundervisningen2019Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The use of information- and communication technology (ICT) has increased in education in recent years. After a previous literature study, a notable rift was discovered in the research since the combination of ICT and mathematics education has not been thoroughly explored. There is inadequate research on teachers’ conceptions of ICT in mathematics education, even though digital competence and digital tools are part of teachers’ everyday lives.

    The purpose of this study is to provide knowledge about teachers’ different experiences of ICT in mathematics teaching. In order to achieve this purpose, three questions were formed which were; what ICT is for teachers, how they use ICT in mathematics teaching, and what aspects teachers distinguish in the use of ICT that can influence mathematics teaching. Data was collected through semi-structured interviews with five primary school teachers. This study uses phenomenography as its theoretical base.

    The different conceptions that derived from the data shaped the outcome space for this study. The outcome space consists of four conceptions of ICT in mathematics teaching that to some extent have been arranged hierarchically by quality: ICT as digital tools and skills training, as tools for communication, as tools for assessment and documentation, and as tools for mathematical learning. There were connections between the outcome space and the previous research, among them digital tools and apps. However, there also emerged a few gaps in the previous research, where several of the parts that were seen in the result could not be compared with previous research.

  • 267.
    Månsson, Kristofer
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Developing a Liu estimator for the negative binomial regression model: method and application2013In: Journal of Statistical Computation and Simulation, ISSN 0094-9655, E-ISSN 1563-5163, Vol. 83, no 9, p. 1773-1780Article in journal (Refereed)
    Abstract [en]

    This paper introduces a new shrinkage estimator for the negative binomial regression model that is a generalization of the estimator proposed for the linear regression model by Liu [A new class of biased estimate in linear regression, Comm. Stat. Theor. Meth. 22 (1993), pp. 393–402]. This shrinkage estimator is proposed in order to solve the problem of an inflated mean squared error of the classical maximum likelihood (ML) method in the presence of multicollinearity. Furthermore, the paper presents some methods of estimating the shrinkage parameter. By means of Monte Carlo simulations, it is shown that if the Liu estimator is applied with these shrinkage parameters, it always outperforms ML. The benefit of the new estimation method is also illustrated in an empirical application. Finally, based on the results from the simulation study and the empirical application, a recommendation regarding which estimator of the shrinkage parameter that should be used is given.

  • 268.
    Månsson, Kristofer
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics.
    Issues of multicollinearity and conditional heteroscadasticity in time series econometrics2012Doctoral thesis, comprehensive summary (Other academic)
  • 269.
    Månsson, Kristofer
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Issues of multicollinearity and conditional heteroscedasticy in time series econometrics2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This doctoral thesis consists of four chapters all related to the field of time series econometrics. The main contribution is firstly the development of robust methods when testing for Granger causality in the presence of generalized autoregressive conditional heteroscedasticity (GARCH) and causality-in-variance (i.e. spillover) effects. The second contribution is the development of different shrinkage estimators for count data models which may be used when the explanatory variables are highly inter-correlated.

    The first essay investigated the effect of spillover on some tests for causality in a Granger sense. As a remedy to the problem of over-rejection caused by the spillover effects White’s heteroscedasticity consistent covariance matrix is proposed. In the second essay the effect of GARCH errors on the statistical tests for Granger causality is investigated. Here some wavelet denoising methods are proposed and by means of Monte Carlo simulations it is shown that the size properties of the tests based on wavelet filtered data is better than the ones based on raw data.

    In the third and fourth essays ridge regression estimators for the Poisson and negative binomial (NB) regression models are investigated respectively. Then finally in the fifth essaya Liu type of estimator is proposed for the NB regression model. By using Monte Carlo simulations it is shown that the estimated MSE is lower for the ridge and Liu type of estimators than maximum likelihood (ML).

  • 270.
    Månsson, Kristofer
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics.
    Kibria, B M Golam
    Florida International University, USA.
    Shukur, Ghazi
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics.
    Improved Ridge Regression Estimators for Binary Choice Models: An Empirical Study2014In: International Journal of Statistics in Medical Research, ISSN 1929-6029, Vol. 3, no 3, p. 257-265Article in journal (Refereed)
    Abstract [en]

    This paper suggests some new estimators of the ridge parameter for binary choice models that may be applied in the presence of a multicollinearity problem. These new ridge parameters are functions of other estimators of the ridge parameter that have shown to work well in the previous research. Using a simulation study we investigate the mean square error (MSE) properties of these new ridge parameters and compare them with the best performing estimators from the previous research. The results indicate that we may improve the MSE properties of the ridge regression estimator by applying the proposed estimators in this paper, especially when there is a high multicollinearity between the explanatory variables and when many explanatory variables are included in the regression model. The benefit of this paper is then shown by a health related data where the effect of some risk factors on the probability of receiving diabetes is investigated.

  • 271.
    Månsson, Kristofer
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Kibria, B. M. Golam
    Department of mathematics and Statistics, Florida International University, Miami, Florida, USA.
    Shukur, Ghazi
    Jönköping University, Jönköping International Business School, JIBS, Statistics. The Linnaeus University, Department of Economics and Statistics, Växjö, Sweden.
    Some Liu Type Estimators for the dynamic OLS estimator: With an application to the carbon dioxide Kuznets curve for Turkey2017In: Communications in Statistics: Case Studies, Data Analysis and Applications, ISSN 2373-7484, Vol. 3, no 3-4, p. 55-61Article in journal (Refereed)
    Abstract [en]

    This paper suggests some Liu type shrinkage estimators for the dynamic ordinary least squares (DOLS) estimator that may be used to combat the multicollinearity problem. DOLS is an estimator suggested to solve the finite sample bias of OLS caused by endogeneity issue when estimating regression models based on cointegrated variables. In this paper using simulation techniques it is shown that multicollinearity and non-normality of the error term is a problem in finite samples for the DOLS model. The merit of proposed Liu type estimator are shown by means of a Monte Carlo simulation study and using an empirical application.

  • 272.
    Månsson, Kristofer
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Kibria, B. M. Golam
    Department of Mathematics and Statistics, Florida International University, Miami, USA.
    Shukur, Ghazi
    Jönköping University, Jönköping International Business School, JIBS, Statistics. Department of Economics and Statistics, Linnaeus University, Växjö, Sweden.
    Sjölander, Pär
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    On the Estimation of the CO2 Emission, Economic Growth and Energy Consumption Nexus Using Dynamic OLS in the Presence of Multicollinearity2018In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, no 5, article id 1315Article in journal (Refereed)
    Abstract [en]

    This paper introduces shrinkage estimators (Ridge DOLS) for the dynamic ordinary least squares (DOLS) cointegration estimator, which extends the model for use in the presence of multicollinearity between the explanatory variables in the cointegration vector. Both analytically and by using simulation techniques, we conclude that our new Ridge DOLS approach exhibits lower mean square errors (MSE) than the traditional DOLS method. Therefore, based on the MSE performance criteria, our Monte Carlo simulations demonstrate that our new method outperforms the DOLS under empirically relevant magnitudes of multicollinearity. Moreover, we show the advantages of this new method by more accurately estimating the environmental Kuznets curve (EKC), where the income and squared income are related to carbon dioxide emissions. Furthermore, we also illustrate the practical use of the method when augmenting the EKC curve with energy consumption. In summary, regardless of whether we use analytical, simulation-based, or empirical approaches, we can consistently conclude that it is possible to estimate these types of relationships in a considerably more accurate manner using our newly suggested method.

  • 273.
    Månsson, Kristofer
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Shukur, Ghazi
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Kibria, B. M. Golam
    Department of Mathematics and Statistics, Florida International University, Miami, Florida, USA.
    Performance of Some Ridge Regression Estimators for the Multinomial Logit Model2018In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 47, no 12, p. 2795-2804Article in journal (Refereed)
    Abstract [en]

    This article considers several estimators for estimating the ridge parameter k for multinomial logit model based on the work of Khalaf and Shukur (2005), Alkhamisi et al. (2006), and Muniz et al. (2012). The mean square error (MSE) is considered as the performance criterion. A simulation study has been conducted to compare the performance of the estimators. Based on the simulation study we found that increasing the correlation between the independent variables and the number of regressors has negative effect on the MSE. However, when the sample size increases the MSE decreases even when the correlation between the independent variables is large. Based on the minimum MSE criterion some useful estimators for estimating the ridge parameter k are recommended for the practitioners

  • 274.
    Månsson, Kristofer
    et al.
    Jönköping University, Jönköping International Business School.
    Sjölander, Pär
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics.
    Testing for nonlinear panel unit roots under cross-sectional dependency: with an application to the PPP hypothesis2014In: Economic Modelling, ISSN 0264-9993, E-ISSN 1873-6122, Vol. 38, p. 121-132Article in journal (Refereed)
    Abstract [en]

    In this paper we propose a number of nonlinear panel unit root tests that are robust to cross-sectional dependency. These tests may be used to test the null hypothesis of non-stationarity against the alternative that some or all of the time series in the system of equations follow a stationary exponential smooth transition autoregressive (ESTAR) process. In contrast to previous research we relax the assumption that the cross-correlation structure is driven by a common-factor and consider an endogenous correlation structure. Based on the size and power results from the Monte Carlo simulations we recommend using the Wald version of our cross-sectional dependent robust nonlinear panel unit root (CDR-NPU) method.

    Finally, in an empirical application we demonstrate that our more powerful nonlinear method, in contrast to previous methods, can provide support for PPP even in smaller samples. In consistency with the univariate tests in Bahmani-Oskooee et al. (2008) our CDR-NPU tests support the theory that less industrialized economies exhibit stronger and more distinct nonlinear adjustment patterns towards PPP.

  • 275.
    Nelson, Johanna
    Jönköping University, School of Education and Communication.
    Föra och följa matematiska resonemang: En fenomenografisk studie kring lärares uppfattningar av undervisning som utvecklar elevernas förmåga att resonera muntligt2018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The importance of communication and reasoning in teaching is clearly explained in the Swedish syllabus for mathematics. The purpose of the study is to visualize teachers' perceptions of teaching that give students in grades 4-6 the opportunity to develop the oral ability to lead and follow mathematical reasoning. Using a qualitative phenomenological approach based on questions about the types of conversations that the teachers describe and how they support the students to develop the ability, 5 semi-structured interviews were conducted. The phenomenological analysis led to two outcome areas, one with 4 description categories for forms of discussion, and another with 8 description categories about support. The conclusion of the result is that the teachers describe several conversational forms used in the classroom and which teachers perceive as beneficial for developing the students' ability. The support given has different functions and all can be considered important, whether used individually or simultaneously.

  • 276.
    Nooi Asl, M.
    et al.
    Department of Statistics, Faculty of Mathematical Sciences, University of Tabriz, Tabriz, Iran.
    Bevrani, Hossein
    Department of Statistics, Faculty of Mathematical Sciences, University of Tabriz, Tabriz, Iran.
    Arabi Belaghi, Reza
    Department of Statistics, Faculty of Mathematical Sciences, University of Tabriz, Tabriz, Iran.
    Månsson, Kristofer
    Jönköping University, Jönköping International Business School, JIBS, Statistics. Jönköping University, Jönköping International Business School, JIBS, Economics.
    Ridge-type shrinkage estimators in generalized linear models with an application to prostate cancer data2019In: Statistical papers, ISSN 0932-5026, E-ISSN 1613-9798Article in journal (Refereed)
    Abstract [en]

    This paper is concerned with the estimation of the regression coefficients for the generalized linear models in the situation where a multicollinear issue exists and when it is suspected that some of the regression coefficients may be restricted to a linear subspace. Accordingly, as a solution to this issue, we propose a new Stein-type shrinkage ridge estimation approach. We provide the analytic expressions for the asymptotic biases and risks of the proposed estimators and investigate their relative performance with respect to the unrestricted ridge regression estimator. Monte-Carlo simulation studies are conducted to appraise the performance of the underlying estimators in terms of their simulated relative efficiencies. It is clear from both the analytical results and the simulation study that the Stein-type shrinkage ridge estimators dominate the usual ridge regression estimator in the entire parameter space. Finally an empirical application is provided where prostate cancer data is analyzed to show the practical usefulness of the suggested approach. Based on the results from the different parts of this paper, we find that the new method developed would be useful for the practitioners in various research areas such as economics, insurance data and medicine. 

  • 277. Nylen, Per
    et al.
    Hansbo, Anita
    Friis, Martin
    Pejryd, Lars
    Investigation of particle in-flight characteristics during atmospheric plasma spraying of yttria stabilized ZrO2: Part 2. Modeling2001In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 10, no 2, p. 359-366Article in journal (Refereed)
    Abstract [en]

    Yttria stabilized ZrO2 particle in-flight characteristics in an Ar-H2 atmospheric plasma jet have been studied using analytical and experimental techniques. In the previous article,[1] the primary gas flow, plasma composition, current, and powder feed rate were systematically varied and particle surface temperatures, velocities, and size distributions measured and statistically analyzed. In this paper, a mathematical model for the plasma flow and particle characteristics is presented. Model predictions are compared with the experimental results in Ref 1 and a reasonable correlation is found. A statistical investigation (composite cubic face (CCF)) is performed on the particle predictions, giving fast and simple relationships between gun parameters and particle in-flight properties. The statistical and theoretical models that are presented here combine to form a powerful and cost-effective tool, which can be used in the evaluation and optimization of spray parameters off-line.

  • 278. Nylén, Per
    et al.
    Bolot, Rodolphe
    Hansbo, Anita
    Coddet, Christian
    Modelling and measurements of particle in-flight characteristics of atmospheric plasma sprayed yttria stabilised zirconia1999In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 891, p. 236-245Article in journal (Refereed)
    Abstract [en]

    Stabilised ZrO2 particle in flight characteristics in an Ar-H2 atmospheric plasma jet have been studied using analytical and experimental techniques. A commercial code was used to simulate the plasma flow. A standard k-ε turbulence model was used. Powder particle velocity, temperature history and trajectory were calculated using a stochastic discrete particle model and compared with measurements. A good correlation was found between predictions and measurements. Relationships between the sprayed particle velocity, temperature and size were investigated and a clear correlation was found. The method presented here seems to be a powerful and cost-effective tool, which could be used to optimise spray parameters off-line.

  • 279.
    Olofsson, Peter
    et al.
    Jönköping University, School of Engineering, JTH, Physics and Mathematics and Chemical Engineering. Department of Mathematics, Trinity University, United States.
    Livingstone, Kevin
    Department of Biology, Trinity University, United States.
    Humphreys, Joshua
    Department of Biology, Trinity University, United States.
    Steinman, Douglas
    Department of Mathematics, Trinity University, United States.
    The probability of speciation on an interaction network with unequal substitution rates2016In: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 278, p. 1-4Article in journal (Refereed)
    Abstract [en]

    Speciation is characterized by the development of reproductive isolating barriers between diverging groups. A seminal paper of a mathematical model of speciation was published by Orr (1995), extended by Livingstone et al. (2012) to incorporate interaction networks. Here, we further develop the model to take into account the possibility of different substitution rates for network nodes of different connectivity. Mathematically, this amounts to sampling nodes from an undirected graph where the inclusion probability for a given node depends on its degree (number of connecting edges). We establish formulas for the rate of speciation and identify a crucial parameter that is a measure of the deviation from simple random sampling.

  • 280.
    Olsson, Julia
    et al.
    Jönköping University, School of Education and Communication.
    Tholin, Amanda
    Jönköping University, School of Education and Communication.
    Blockprogrammering i matematikämnet: En litteraturöversikt om visuell programmering i årskurs F-62019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Elever i Sverige ska från och med höstterminen 2018 lära sig programmering och det är nu ett obligatoriskt område i det centrala innehållet i matematikämnet. Programmering är ett outforskat område för många verksamma matematiklärare som menar att de inte har tillräcklig kompetens och kunskap för att undervisa om det. Denna litteraturstudie syftar därför, till att genom didaktisk forskning, beskriva visuell blockbaserad programmering i matematikundervisningen då elever i årskurs 4-6 ska erbjudas möjligheten att arbeta med visuella programmeringsmiljöer. I resultatdelen presenteras undervisningsmetoder, lärarstilar och utmaningar vid användning av blockbaserade programmeringsmiljöer. Debugging visar sig vara en utmärkande metod och en process som kan utveckla elevers lärande. Blockbaserade program kan medföra att elever fokuserar på annat än matematiska koncept, men med en utförlig lärarhandledning skulle eventuellt den problematiken kunna minskas. Studien visar hur och varför blockbaserade programmeringsmiljöer används för att utveckla programmering.

  • 281.
    Omer, Talha
    et al.
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Hussein, Z.
    Qasim, Muhammad
    Department of Statistics and Computer Science, University of Veterinary and Animal sciences, Lahore, Pakistan.
    Optimized monitoring network of Pakistan2019Conference paper (Refereed)
  • 282.
    Ossowicki, Ellen
    Jönköping University, School of Education and Communication, HLK, Disciplinary Research.
    Dyskalkyli: En form av matematiksvårigheter2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien har varit att skapa en översikt om vad diagnosen dyskalkyli innebär genom att granska vetenskapliga artiklar ifrån 2011 - 2017. Syftet besvaras genom följande frågeställningar. Hur definieras diagnosen dyskalkyli? Vilka drabbas av dyskalkyli? Vilka samband finns det till andra diagnoser? Vad finns det för kritik mot dyskalkyli?

    För att få svar på dessa frågor har olika söktjänster använts för att hitta vetenskapligt granskad litteratur. Den litteratur som har använts är till mesta del riktad till grundskolans år. Då forskningen är mycket begränsad består resultatet endast av internationell litteratur. Resultatet visar att de flesta forskarna är överens om att det är en existerande diagnos som behöver specialpedagogiska insatser. Dyskalkyli som begrepp syftar på att det finns en medfödd svårighet att lära sig matematik, som verkar vara ärftligt betingad. Förekomsten av dyskalkyli verkar enligt resultatet vara 3 - 7%. Det finns starka kopplingar till andra diagnoser som dyslexi och ADHD.

    Följaktligen finns det ett stort behov av fortsatt forskning kring dyskalkyli, både internationellt och nationellt. 

  • 283.
    Papadopoulos, Ioannis
    et al.
    Aristotle University, Thessaloniki, Greece.
    Gunnarsson, Robert
    Jönköping University, School of Education and Communication, HLK, Praktiknära utbildningsforskning (PUF), Mathematics Education Research.
    The use of ‘mental’ brackets when calculating arithmetic expressions2018In: Proceedings of the 42nd Conference of the International Group for the Psychology of Mathematics Education: Vol. 3 / [ed] E. Bergqvist, M. Österholm, C. Granberg & L. Sumpter, Umeå: PME , 2018, p. 451-458Conference paper (Refereed)
  • 284.
    Persson, Angelica
    et al.
    Jönköping University, School of Education and Communication.
    Westergren, Cecilia
    Kooperativt lärande i matematikundervisning: Förtjänster och fallgropar2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 285.
    Pettersson, Johan
    Jönköping University, School of Education and Communication.
    Historiska talsystem i matematikböcker: En läromedelsanalys av utmaningar och möjligheter med uppgifter om historiska talsystem2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Historical number systems are since 2011, when the new curriculum was introduced, part of the mathematical subject. That means that educational mathematical workbooks that intend to contain what is in the course plan surely will include tasks related to the Babylonian or the Egyptian number systems, for instance. The purpose of this analysis is to explore tasks of this subject. What is the challenge of these tasks? How can these tasks develop the mathematical skills of pupils? These are the two questions this study seeks to answer. Through a qualitative analysis of four different workbooks for year 4 to 6, various tasks are presented in terms of challenges and possibilities.

     

    The four analysed workbooks are all used in Swedish schools; Pixel 5a, Eldorado 6b, Koll på matematik 6b (Understanding mathematics) and Mera favoritmatematik 6a (More favorite mathematics). A wide range of tasks are analysed with a theoretical framework concerning conceptual and creative challenges (Jäder, 2019; Lithner, 2008). There are many similar tasks but also many different and unique ones which allows for different kinds of challenges and possibilities to develop mathematical skills. Some tasks have the potential to both challenge students conceptually and/or creatively but also develop their mathematical skills. The deciding factor whether a task has the potential to develop students’ mathematical skills is usually the amount of information or instructions provided by the workbook.

  • 286.
    Pettersson, Johan
    et al.
    Jönköping University, School of Education and Communication.
    Sidenvik, Emil
    Jönköping University, School of Education and Communication.
    Talsystem i grundskolan: Effekter av kunskap om det hindu-arabiska tiobassystemet och undervisning om de historiska talsystemen.2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med den här litteraturstudien är att kartlägga forskning om hur kunskap om det hindu-arabiska tiobassystemet påverkar elevers aritmetiska förmåga, samt vad forskning säger om vad undervisning om andra historiska talsystem har för påverkan på elevers förståelse av det hindu-arabiska tiobassystemet. Syftet uppnåddes med att besvara följande frågeställningar. I vilken ålder bör elever undervisas om talsystem? Finns det ett samband mellan undervisning om olika talsystem och elevers förståelse av tiobassystemet, samt vilken betydelse har kunskap om tiobassystemet för elevers aritmetiska förmågor? Materialet samlades in genom en systematisk sökningsprocedur innefattande sex databaser, som resulterade i nio olika vetenskapliga texter.

     

    Studien visar att undervisning om talsystem bör äga rum så tidigt som möjligt, då kunskap om det hindu-arabiska tiobassystemet är viktigt för elevers aritmetiska förmåga. Studien visade också att undervisning om historiska kulturers talsystem främst har två positiva effekter. Dels kan undervisning med det romerska talsystemet hjälpa elever som har addition- och subtraktionssvårigheter, dels har sådan undervisning också en positiv effekt på elevers förståelse av det hindu-arabiska tiobassystemet. Slutligen spelar kunskap om det hindu-arabiska tiobassystemet stor roll för elevers aritmetiska förmåga eftersom den här kunskapen enligt flera studier har visat sig vara en grundläggande kompetens.

  • 287.
    Qasim, Muhammad
    et al.
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Amin, Muhammad
    Department of Statistics, University of Sargodha, Sargodha, Pakistan.
    Amanullah, Muhammad
    Department of Statistics, Bahauddin Zakariya University, Multan, Pakistan.
    On the performance of some new Liu parameters for the gamma regression model2018In: Journal of Statistical Computation and Simulation, ISSN 0094-9655, E-ISSN 1563-5163, Vol. 88, no 16, p. 3065-3080Article in journal (Refereed)
    Abstract [en]

    The maximum likelihood (ML) method is used to estimate the unknown Gamma regression (GR) coefficients. In the presence of multicollinearity, the variance of the ML method becomes overstated and the inference based on the ML method may not be trustworthy. To combat multicollinearity, the Liu estimator has been used. In this estimator, estimation of the Liu parameter d is an important problem. A few estimation methods are available in the literature for estimating such a parameter. This study has considered some of these methods and also proposed some new methods for estimation of the d. The Monte Carlo simulation study has been conducted to assess the performance of the proposed methods where the mean squared error (MSE) is considered as a performance criterion. Based on the Monte Carlo simulation and application results, it is shown that the Liu estimator is always superior to the ML and recommendation about which best Liu parameter should be used in the Liu estimator for the GR model is given. 

  • 288.
    Qasim, Muhammad
    et al.
    Department of Statistics and Computer Science, University of Veterinary and Animal sciences, Lahore, Pakistan.
    Amin, Muhammad
    Department of Statistics, University of Sargodha, Sargodha, Pakistan.
    Azam, Muhammad
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Omer, Talha
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    On Almost Unbiased Ridge Estimator in the Poisson Regression Model2019Conference paper (Refereed)
  • 289.
    Qasim, Muhammad
    et al.
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Amin, Muhammad
    Department of Statistics, University of Sargodha, Sargodha, Pakistan.
    Omer, Talha
    Department of Statistics and Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Performance of some new Liu parameters for the linear regression model2019In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415XArticle in journal (Refereed)
    Abstract [en]

    This article introduces some Liu parameters in the linear regression model based on the work of Shukur, Månsson, and Sjölander. These methods of estimating the Liu parameter d increase the efficiency of Liu estimator. The comparison of proposed Liu parameters and available methods has done using Monte Carlo simulation and a real data set where the mean squared error, mean absolute error and interval estimation are considered as performance criterions. The simulation study shows that under certain conditions the proposed Liu parameters perform quite well as compared to the ordinary least squares estimator and other existing Liu parameters. 

  • 290.
    Qasim, Muhammad
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Kibria, B. M. G.
    Department of Mathematics and Statistics, Florida International University, Miami, FL, USA.
    Månsson, Kristofer
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Sjölander, Pär
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    A new Poisson Liu Regression Estimator: method and application2019In: Journal of Applied Statistics, ISSN 0266-4763, E-ISSN 1360-0532Article in journal (Refereed)
    Abstract [en]

    This paper considers the estimation of parameters for the Poisson regression model in the presence of high, but imperfect multicollinearity. To mitigate this problem, we suggest using the Poisson Liu Regression Estimator (PLRE) and propose some new approaches to estimate this shrinkage parameter. The small sample statistical properties of these estimators are systematically scrutinized using Monte Carlo simulations. To evaluate the performance of these estimators, we assess the Mean Square Errors (MSE) and the Mean Absolute Percentage Errors (MAPE). The simulation results clearly illustrate the benefit of the methods of estimating these types of shrinkage parameters in finite samples. Finally, we illustrate the empirical relevance of our newly proposed methods using an empirically relevant application. Thus, in summary, via simulations of empirically relevant parameter values, and by a standard empirical application, it is clearly demonstrated that our technique exhibits more precise estimators, compared to traditional techniques - at least when multicollinearity exist among the regressors.

  • 291.
    Robertsson, Morgan
    Jönköping University, School of Education and Communication.
    Att synliggöra yrketslivets matematikbehov för fordons- och transportelever.2013Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 292.
    Rosdal, Ida
    et al.
    Jönköping University, School of Education and Communication.
    Röhs, Julia
    Jönköping University, School of Education and Communication.
    Samtal i matematikundervisningen: En kvalitativ studie om lärares syn på samtal2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med den här studien är att ta reda på vilken syn lärare har på samtal i matematik-undervisningen samt vilken roll de anser sig ha i dessa. De frågeställningar som studien utgår ifrån är följande:

    - Vad anser lärare att samtal har för syfte i matematikundervisningen?

    - Vilken roll anser sig lärare ha i samtal som sker i matematikundervisningen?

    Vi har valt att använda oss av en kvalitativ metod med intervjuer som datainsamlingsmetod för att få svar på frågorna. De som har intervjuats är sex matematiklärare som är verksamma i årskurserna 1-6. Respondenterna har valts ut genom bekvämlighetsurval.

    Resultatet visar att lärarna ser samtalen som ett sätt att göra matematikundervisningen varierad och vardagsnära. Syftet med samtalen är främst att utveckla elevernas matematiska förståelse. Samtalen ger också möjlighet för eleverna att samarbeta och förklara för andra hur de tänker. Lärarna beskriver att de i samtalen kan få en uppfattning om elevernas tankar och förståelse. Av lärarnas beskrivningar av sin roll i samtalen i matematikundervisningen framgår det att de intar olika roller i olika samtalssituationer. Dessa olika roller är leda, lyssna, undervisa och uppmuntra.

     

  • 293.
    Sahamkhadam, Maziar
    et al.
    Linnaeus University, Växjö, Sweden.
    Stephan, Andreas
    Jönköping University, Jönköping International Business School, JIBS, Center for Family Enterprise and Ownership (CeFEO). Jönköping University, Jönköping International Business School, JIBS, Economics.
    Östermark, Ralf
    Åbo Akademi, Turku, Finland.
    Portfolio optimization based on GARCH-EVT-Copula forecasting models2018In: International Journal of Forecasting, ISSN 0169-2070, E-ISSN 1872-8200, Vol. 34, no 3, p. 497-506Article in journal (Refereed)
    Abstract [en]

    This study uses GARCH-EVT-copula and ARMA-GARCH-EVT-copula models to perform out-of-sample forecasts and simulate one-day-ahead returns for ten stock indexes. We construct optimal portfolios based on the global minimum variance (GMV), minimum conditional value-at-risk (Min-CVaR) and certainty equivalence tangency (CET) criteria, and model the dependence structure between stock market returns by employing elliptical (Student- t and Gaussian) and Archimedean (Clayton, Frank and Gumbel) copulas. We analyze the performances of 288 risk modeling portfolio strategies using out-of-sample back-testing. Our main finding is that the CET portfolio, based on ARMA-GARCH-EVT-copula forecasts, outperforms the benchmark portfolio based on historical returns. The regression analyses show that GARCH-EVT forecasting models, which use Gaussian or Student- t copulas, are best at reducing the portfolio risk.

  • 294.
    Sahlberg, Jonas
    Jönköping University, School of Education and Communication.
    Matematikvägen: Ett grepp att möta matematikintresserade elever inför och på gymnasiet?2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Undersökningens syfte har varit att ta del av likheter och skillnader i gymnasieelevers uppfattningar om Matematikvägen, utifrån frågeställningen ”Vilka upplevelser har eleverna av Matematikvägen?”. Metoden för undersökningen har varit intervju.

    Matematikvägen är ett grepp att möta elever med ett stort matematikintresse inför och på gymnasiet. Detta görs genom att eleverna får möjlighet att läsa ungefär halva gymnasiets Matematik A redan under sista terminen på grundskolan. Eleverna ligger på så sätt en termin före de som läser matematiken på normal fart vilket innebär att de det sista året på gymnasiet kan välja att läsa linjär algebra på högskolan. Undersökningen visar på att det finns svårigheter med att ha en matematiksatsning som å ena sidan vänder sig till elever med ett stort matematikintresse och å andra sidan erbjuder eleverna att läsa fler kurser i slutet av gymnasiet. En fördel med Matematikvägen är att den kan fungera som en bro mellan matematiken i grundskolan och gymnasiet och vidare upp på högskolan. Men för de elever som eventuellt har valt att läsa på Matematikvägen utifrån ett stort matematikintresse har inte Matematikvägen något speciellt att erbjuda.

  • 295.
    Salman, Khalik
    et al.
    Department of Social Sciences, Mid Sweden University.
    Arnesson, Leif
    Department of Social Sciences, Mid Sweden University.
    Sörensson, Anna
    Department of Social Sciences, Mid Sweden University.
    Shukur, Ghazi
    Jönköping University, Jönköping International Business School, JIBS, Economics.
    Estimating the Swedish and Norwegian international tourism demand using (ISUR) technique2010In: Scandinavian Journal of Hospitality and Tourism, ISSN 1502-2250, E-ISSN 1502-2269, Vol. 10, no 4, p. 395-410Article in journal (Refereed)
    Abstract [en]

    This paper estimates the demand for tourism to Sweden and Norway from five countries: Denmark, the United Kingdom, Switzerland, Japan, and the United States. For each visiting country, and for selected regions in Sweden and Norway, we specify separate equations by including relative information. We then estimate these equations using Zellner's Iterative Seemingly Unrelated Regressions (ISUR). The benefit of this model is that the ISUR estimators utilize the information present in the error correlation of the cross regressions (or equations) and hence are more efficient than single equation estimation methods such as ordinary least squares. Monthly time series data from January 1993 to December 2006 are used. The results show that the consumer price index, some lagged dependent variables, and several monthly dummies (representing seasonal effects) have a significant impact on the number of visitors to the SW6 region in Sweden and Tröndelag in Norway. We also find that, in at least some cases, relative prices and exchange rates have a significant effect on international tourism demand.

  • 296.
    Sandberg, Lina
    et al.
    Jönköping University, School of Education and Communication, HLK, Disciplinary Research.
    Stenberg, Ditte Maria
    Jönköping University, School of Education and Communication, HLK, Disciplinary Research.
    Högpresterande elever i matematik: Elevers reflektioner över sitt upplevda stöd och sin matematiska förmåga2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag har vi en skola för alla där varje elev ska få möjlighet att utvecklas efter sina förutsättningar och behov. Den här studien handlar om hur högpresterande elever i matematik upplevde grundskolan. Syftet med studien är att belysa vilket stöd högpresterande elever fått och velat ha under sina år på grundskolan och samtidigt undersöka hur de definierar sin förmåga i matematik.

    Tretton semistrukturerade intervjuer genomfördes utifrån en kvalitativ metod med elever på gymnasiet. Resultatet visar att de högpresterande eleverna har svårt att definiera sina kunskaper och förmågor. Studiens fokus ligger vid vilket stöd de intervjuade eleverna upplevt och vilket stöd de önskat. Det som kom fram är snarare bristen på stöd och utvecklande möjligheter. Eleverna har varken upplevt berikning eller acceleration i någon större utsträckning, men individualisering och differentiering har skett på skiftande sätt. Eleverna i studien önskar att de hade varit nivågrupperade och att de hade fått mer enskild hjälp, bättre stöd och fler utmaningar.

  • 297.
    Sattar, Tehmina
    et al.
    Department of Sociology, Bahauddin Zakariya University, Multan, Pakistan.
    Ullah, Muhammad Imdad
    Lyallpur Business School, Government College University, Faisalabad.
    Qasim, Muhammad
    Department of Statistics & Computer Science, University of Veterinary and Animal Sciences, Lahore, Pakistan.
    Warraich, Imtiaz Ahmad
    Department of Sociology, Bahauddin Zakariya University, Multan, Pakistan.
    Role of job designs in determining employees’ work motivation in banking sector of Multan City, Pakistan2019In: Review of Economics and Development Studies, ISSN 2519-9692, Vol. 5, no 1, p. 145-154Article in journal (Refereed)
    Abstract [en]

    This article presents theoretical and empirical underpinnings between job designs and employees’ work motivation in banking sector of Multan city, Pakistan. The study adopted a cross-sectional survey research design in which 362 employees participated through simple random sampling technique. The findings of the study revealed that female employees are more motivated towards their jobs than male employees. Moreover, job characteristics and job rotation are high among senior bank employees having experience greater than 12 years. The study concluded that job enrichment is the highest influential factor in determining employees work motivation while quality of work life is negatively influencing their enthusiasm level towards job. In the wake of new technological transformations, academic insight into the current work would further guide the policy makers for designing the jobs for banking sector through decentralization of managerial powers, changing in accordance with the global trends, as well as applying autonomous, mastery oriented and purposely directed policies.

  • 298.
    Schill, Johan
    et al.
    Jönköping University.
    Emma, Richardsdotter
    Jönköping University.
    Undervisning om analog respektive digital klocka: En litteraturstudie2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna litteraturstudie är att ge en bild av hur matematikdidaktisk forskning beskriver elevers förståelse för den analoga respektive digitala klockan i grundskolans tidigare år. För att ta reda på detta kommer följande frågeställningar användas: vilka svårigheter och missuppfattningar kan elever visa i sin förståelse för den analoga respektive digitala klockan? Vilka arbetssätt och metoder har visat sig kunna utveckla elevers lärande om klockan i undervisning?

    Studien har baserats på vetenskapliga artiklar som funnits via en systematisk sökprocess i olika databaser och kedjesökning.

    I studien konstateras att forskare lyfter fram olika arbetsmetoder i undervisning rörande klockan, men även likheter finns. Vi har sett att elevers mognad spelar en viktig roll när det kommer till undervisning om klockan, men hur undervisningen ska bedrivas kan dock se olika ut. Vi presenterar även forskarnas syn på vilka vanliga svårigheter och missuppfattningar som elever kan visa när de ställs inför analog eller digital representation av tid. Exempelvis är timvisaren och minutvisaren något som elever vanligtvis har svårt att särskilja. Vidare är forskarna eniga om att elever har lättare att förstå och avläsa den digitala klockan jämfört med den analoga.

  • 299.
    Shukur, Ghazi
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Statistics.
    Doszyń, Mariusz
    Szczecin University, Econometrics and Statistics Institute.
    Dmytrów, Krzysztof
    Szczecin University, Econometrics and Statistics Institute.
    Comparison of the effectiveness of forecasts obtained by means of selected probability functions with respect to forecast error distributions2017In: Communications in statistics. Simulation and computation, ISSN 0361-0918, E-ISSN 1532-4141, Vol. 46, no 5, p. 3667-3679Article in journal (Refereed)
    Abstract [en]

    The Forecasting of sales in a company is one of the crucial challenges that must be faced. Nowadays, there is a large spectrum of methods that enable making reliable forecasts. However, sometimes the nature of time series excludes many well-known and widely used forecasting methods (e.g. econometric models). Therefore, the authors decided to forecast on the basis of a seasonally adjusted median of selected probability distributions. The obtained forecasts were verified by means of distributions of the Theil U2 coefficient and unbiasedness coefficient.

  • 300.
    Shukur, Ghazi
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics.
    Hussain, Shakir
    University of Birmingham, UK.
    Al-Alak, Mehdi
    Bagdad University, Irak.
    Conditional Two Level Mixture with Known Mixing Proportions: Applications to School and Student Level Overweight and Obesity Data from Birmingham, England2014In: International Journal of Statistics in Medical Research, ISSN 1929-6029, Vol. 3, no 3, p. 298-308Article in journal (Refereed)
    Abstract [en]

    Two Level (TL) models allow the total variation in the outcome to be decomposed as level one and level two or ‘individual and group’ variance components. Two Level Mixture (TLM) models can be used to explore unobserved heterogeneity that represents different qualitative relationships in the outcome.

    In this paper, we extend the standard TL model by introducing constraints to guide the TLM algorithm towards a more appropriate data partitioning. Our constraints-based methods combine the mixing proportions estimated by parametric Expectation Maximization (EM) of the outcome and the random component from the TL model. This forms new two level mixing conditional (TLMc) approach by means of prior information. The new framework advantages are: 1. avoiding trial and error tactic used by TLM for choosing the best BIC (Bayesian Information Criterion), 2. permitting meaningful parameter estimates for distinct classes in the coefficient space and finally 3. allowing smaller residual variances. We show the benefit of our method using overweight and obesity from Body Mass Index (BMI) for students in year 6. We apply these methods on hierarchical BMI data to estimate student multiple deprivation and school Club effects.

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