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  • 1. Barban, Nicola
    et al.
    de Luna, Xavier
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Lundholm, Emma
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Svensson, Ingrid
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Billari, F. C.
    Causal Effects of the Timing of Life-course Events: Age at Retirement and Subsequent Health2017In: Sociological Methods & Research, ISSN 0049-1241, E-ISSN 1552-8294Article in journal (Refereed)
    Abstract [en]

    n this article, we combine the extensive literature on the analysis of life-course trajectories as sequences with the literature on causal inference and propose a new matching approach to investigate the causal effect of the timing of life-course events on subsequent outcomes. Our matching approach takes into account pre-event confounders that are both time-independent and time-dependent as well as life-course trajectories. After matching, treated and control individuals can be compared using standard statistical tests or regression models. We apply our approach to the study of the consequences of the age at retirement on subsequent health outcomes, using a unique data set from Swedish administrative registers. Once selectivity in the timing of retirement is taken into account, effects on hospitalization are small, while early retirement has negative effects on survival. Our approach also allows for heterogeneous treatment effects. We show that the effects of early retirement differ according to preretirement income, with higher income individuals tending to benefit from early retirement, while the opposite is true for individuals with lower income.

  • 2.
    Hagelberg, Madeleine
    et al.
    Umeå University, Faculty of Science and Technology. Student vid programmet Teknisk Naturvetenskaplig Kemi.
    Lundberg, Lina
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Rosendahl, Marcus
    Umeå University, Faculty of Science and Technology. Student vid programmet Teknisk Fysik.
    Svensson, Ingrid
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    När avsikten är att ge insikt om framtidsutsikterna2007In: Utsikter, insikter, avsikter: universitetspedagogisk konferens i Umeå 27 – 28 februari 2007 / [ed] Mohammad Fazlhashemi och Thomas Fritz, Umeå: Universitetspedagogiskt Centrum, Umeå universitet , 2007, p. 119-120Conference paper (Other academic)
    Abstract [sv]

    För sjunde året i rad genomförs vid Teknisk-naturvetenskapligafakulteten, Umeå universitet ett rekryteringsprojekt i form av mentorskap. En viktig del i projektet är att överbrygga gapet mellan universitet och gymnasieskola samt att väcka intresse för naturvetenskap och teknik. Målet med projektet är att elever som går tredje året på gymnasieskolans naturvetenskapliga och tekniska program ska få vägledning i valet av studier och en inblick i studentlivet. Programstudenter vid fakulteten erbjuds en kurs imentorskap (3p) och får praktik genom att själva vara mentorer åt en gymnasieelev. I kursen behandlas ämnen såsom utformning, ledning och genomförande av ett mentorskapsprojekt, samt även utvärdering och samtalsmetodik. En heldag med populärvetenskapliga föreläsningar och studentsittning är också det en omtyckt del av projektet. Avsikten med denna presentation är att berätta om ett lyckat rekryteringsprojekt som initierats av en student och som leds av anställda och studenter tillsammans. Projektet bygger på mötet mellan människor och vår förhoppning är att kunna vara en inspirationskälla i det viktiga arbete som rekrytering av nya studenter utgör.

  • 3.
    Isaksson, Cristine
    et al.
    Umeå University, Faculty of Social Sciences, Department of Social Work.
    Lindkvist, Marie
    Umeå University, Faculty of Social Sciences, Department of Statistics.
    Svensson, Ingrid
    Umeå University, Faculty of Social Sciences, Department of Statistics.
    När två blir ett: en lyckosam integrering av kurser i kvalitativ och kvantitativ metod i ett unikt samarbete mellan Statisktiska institutionen och institutionen för Socialt arbete2010In: Undervisning på tvären / [ed] Erik Lindenius, 2010, p. 77-92Conference paper (Refereed)
    Abstract [sv]

    Sedan höstterminen 2006 ges en integrerad kurs i kvalitativ och kvantitativ metod på socionomprogrammet vid Umeå universitet. Tidigare ansvarade institutionen för Socialt arbete för en kvalitativ metodkurs och Statistiska institutionen för en kvantitativ metodkurs. Under hösten 2005 kom direktiv från Ledningsgruppen för socionomprogrammet att en integrerad metodkurs skulle startas med början höstterminen 2006. Med integrering som ledord lämnades de kursansvariga från respektive institution med uppdraget att utveckla och genomföra denna nya form av metodkurs - en integrerad metodkurs som saknade motsvarighet vid såväl Umeå universitet som andra lärosäten i Sverige. Kursens pedagogiska upplägg utgår från teorier kring experimentellt lärande vilket tydliggörs genom att kursen är uppbyggd kring en processövning som löper under hela kursen och som integrerar praktiska moment med teori. Arbetet med processövningen sker i grupper om 5-7 studenter. Under de fem terminer som kursen getts har ett intensivt förändrings- och utvecklingsarbete utförts av lärarna på Statistiska institutionen och Institutionen för Socialt arbete. Både studenter och undervisande lärare uttrycker att de är nöjda med det pedagogiska upplägget av den integrerade metodkursen. Genom integreringen har förutsättningar skapats för en fördjupad reflektion hos studenterna kring fördelarna med att använda båda de vetenskapliga angreppssätten kvalitativ och kvantitativ metod.

  • 4.
    Lundberg, Anna
    et al.
    Umeå University, Faculty of Social Sciences, The Demographic Database.
    Svensson, Ingrid
    Umeå University, Faculty of Social Sciences, Centre for Population Studies. Umeå University, Faculty of Social Sciences, Department of Statistics.
    Restored to Society - The Recovering of Mentally Ill Patients in the Northern Parts of Sweden 1893-19022009In: Healthcare Systems and Medical Instiutions / [ed] Astri Andresen, Oslo: Novus AS , 2009Chapter in book (Other academic)
  • 5.
    Mörling, Tommy
    et al.
    Department of Silviculture, SLU, Umeå, Sweden.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Svensson, Ingrid
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Fries, Anders
    Department of Forest Genetics and Plant Physiology,SLU, Umeå, Sweden.
    Ericsson, Tore
    SkogForsk, Sävar, Sweden.
    A method to estimate fibre length distribution in conifers based on wood samples from increment cores2003In: Holzforschung, ISSN 0018-3830, Vol. 57, no 3, p. 248-254Article in journal (Refereed)
    Abstract [en]

    We propose a method to estimate fibre length distribution in conifers based on wood samples from increment cores processed by automatic optical fibre-analysers. Automatic fibre-analysers are unable to distinguish: a) fibres from other tissues, “fines”, and b) cut from uncut fibres. However, our proposed method can handle these problems if the type of distributions that fibre lengths and fines follow is known. In our study the length distributions of fines and fibres were assumed to follow truncated normal distributions, characterised by means and standard deviations of the two distributions. Parameter estimates were obtained by the maximum likelihood method. Wood samples from two 22-year-old Scots pine trees at breast height were used to evaluate the performance of the method. From stem discs at 1.5 m, adjacent samples of 5 mm increment cores and wood pieces were taken. The cores were trimmed 1 mm at each side and samples were, after maceration, analysed in a Kajaani FiberLab 3.0. The results showed that the method works well and gives a possibility to distinguish fine and fibre length distribution.

  • 6.
    Svensson, Ingrid
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    An evaluation of a method to estimate fibre length distributions based on wood samples from increment coresManuscript (Other academic)
  • 7.
    Svensson, Ingrid
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Estimation of wood fibre length distributions from censored mixture data2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The motivating forestry background for this thesis is the need for fast, non-destructive, and cost-efficient methods to estimate fibre length distributions in standing trees in order to evaluate the effect of silvicultural methods and breeding programs on fibre length. The usage of increment cores is a commonly used non-destructive sampling method in forestry. An increment core is a cylindrical wood sample taken with a special borer, and the methods proposed in this thesis are especially developed for data from increment cores. Nevertheless the methods can be used for data from other sampling frames as well, for example for sticks with the shape of an elongated rectangular box.

    This thesis proposes methods to estimate fibre length distributions based on censored mixture data from wood samples. Due to sampling procedures, wood samples contain cut (censored) and uncut observations. Moreover the samples consist not only of the fibres of interest but of other cells (fines) as well. When the cell lengths are determined by an automatic optical fibre-analyser, there is no practical possibility to distinguish between cut and uncut cells or between fines and fibres. Thus the resulting data come from a censored version of a mixture of the fine and fibre length distributions in the tree. The methods proposed in this thesis can handle this lack of information.

    Two parametric methods are proposed to estimate the fine and fibre length distributions in a tree. The first method is based on grouped data. The probabilities that the length of a cell from the sample falls into different length classes are derived, the censoring caused by the sampling frame taken into account. These probabilities are functions of the unknown parameters, and ML estimates are found from the corresponding multinomial model.

    The second method is a stochastic version of the EM algorithm based on the individual length measurements. The method is developed for the case where the distributions of the true lengths of the cells at least partially appearing in the sample belong to exponential families. The cell length distribution in the sample and the conditional distribution of the true length of a cell at least partially appearing in the sample given the length in the sample are derived. Both these distributions are necessary in order to use the stochastic EM algorithm. Consistency and asymptotic normality of the stochastic EM estimates is proved.

    The methods are applied to real data from increment cores taken from Scots pine trees (Pinus sylvestris L.) in Northern Sweden and further evaluated through simulation studies. Both methods work well for sample sizes commonly obtained in practice.

  • 8.
    Svensson, Ingrid
    Umeå University, Faculty of Science and Technology, Mathematics and Mathematical Statistics.
    Estimation of Wood Fibre Length Distributions with Data from Increment Cores2004Licentiate thesis, comprehensive summary (Other academic)
  • 9.
    Svensson, Ingrid
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Pedagogisk meritering: navelskåderi eller tillfälle för gemensam reflektion kring undervisning och lärande?2015In: Universitetspedagogiska konferensen 2015: Gränslös kunskap, Umeå: Umeå universitet , 2015, p. 58-60Conference paper (Other academic)
  • 10.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Science and Technology, Mathematics and Mathematical Statistics.
    de Luna, Sara
    Umeå University, Faculty of Science and Technology, Mathematics and Mathematical Statistics.
    A stochastic EM algorithm to estimate wood fibre length distributions from censored data2007In: Bulletin of the International Statistical Institute, 56th session: Lissboa, August, 2007, 2007Conference paper (Refereed)
  • 11.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Science and Technology, Mathematics and Mathematical Statistics.
    de Luna, Sara
    Umeå University, Faculty of Science and Technology, Mathematics and Mathematical Statistics.
    Asymptotic properties of a stochastic EM algorithm for mixtures with censored data2007Report (Other academic)
  • 12.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Lundholm, Emma
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic and social geography. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    De Luna, Xavier
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Malmbeg, Gunnar
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic and social geography. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Family Life Course and the Timing of Women's Retirement: a Sequence Analysis Approach2015In: Population, Space and Place, ISSN 1544-8444, E-ISSN 1544-8452, Vol. 21, no 8, p. 856-871Article in journal (Refereed)
    Abstract [en]

    Based on longitudinal data from national Swedish registers, family life courses dynamics for all women born 1935 in Sweden are explored for the period 1990-2006. Focusing primarily on the existence and geographical proximity to parents, children and grandchildren, assuming that the family life courses affect the life situation as well as strategic decisions, this longitudinal study uses a holistic approach, analysing how different types of family life courses are associated with socio-economic conditions as well as with the timing of retirement. The primary task was not to identify the causal determinants of work life exit, but rather to unfold how retirement transition is entwined into the different types of family life courses, whereby retirement and family ageing are different sides of a multifaceted transition period. By using sequence analysis, the family life courses were structured into sequences and durations of states and different family life course categories were identified.

    The sequence analyses reveal a complex relation between retirement decisions and having family members around. Early retirement was associated with a category with few relatives but also with a category with two younger generations present, while we found no strong association with early retirement for categories in which the old generation was around for a longer period. Late retirement was associated with belonging to categories characterized by late family formation and having children at home. These differences in retirement behaviour were also significant when controlling for education level, marital status and type of region in a Cox regression.

  • 13.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Social Sciences, Department of Statistics.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Asymptotic properties of a stochastic EM algorithm for mixtures with censored data2010In: Journal of Statistical Planning and Inference, ISSN 0378-3758, E-ISSN 1873-1171, Vol. 140, no 1, p. 111-127Article in journal (Refereed)
    Abstract [en]

    Weak consistency and asymptotic normality is shown for a stochastic EM algorithm for censored data from a mixture of distributions under lognormal assumptions. The asymptotic properties hold for all parameters of the distributions, including the mixing parameter. In order to make parameter estimation meaningful it is necessary to know that the censored mixture distribution is identifiable. General conditions under which this is the case are given. The stochastic EM algorithm addressed in this paper is used for estimation of wood fibre length distributions based on optically measured data from cylindric wood samples (increment cores).

  • 14.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Bondesson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Estimation of wood fibre length distributions from censored data through an EM algorithm2006In: Scandinavian Journal of Statistics, ISSN 0303-6898, E-ISSN 1467-9469, Vol. 33, no 3, p. 503-522Article in journal (Refereed)
  • 15.
    Svensson, Ingrid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Sjöstedt-de Luna, Sara
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Mörling, Tommy
    Fries, Anders
    Ericsson, Tore
    Adjusting for fibre length-biased sampling probability using increment cores from standing trees2007In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 61, no 1, p. 101-103Article in journal (Refereed)
1 - 15 of 15
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