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  • 451.
    von Rosen, Tatjana
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    von Rosen, Dietrich
    Explicit estimators in unbalanced mixed linear models2015Inngår i: Festschrift in honor of professor Ghazi Shukur on the occasion of his 60th birthday / [ed] Thomas Holgersson, Växjö: Linnaeus University Press, 2015, s. 121-125Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The general unbalanced mixed linear model is considered. Throughresampling it is shown how the fixed effects can explicitly be estimated.The obtained estimator is non-linear but unbiased.

  • 452.
    von Rosen, Tatjana
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    von Rosen, Dietrich
    Small area estimation using reduced rank regression models2019Inngår i: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Small area estimation techniques have got a lot of attention during the last decades due to their important applications in survey studies. Mixed linear models and reduced rank regression analysis are jointly used when considering small area estimation. Estimates of parameters are presented as well as prediction of random effects and unobserved area measurements.

  • 453.
    von Rosen, Tatjana
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    von Rosen, Dietrich
    Volaufova, Julia
    A new method for obtaining explicit estimators in unbalanced mixed linear models2017Inngår i: Statistical papers, ISSN 0932-5026, E-ISSN 1613-9798, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The general unbalanced mixed linear model with two variance components is considered. Through resampling it is demonstrated how the fixed effects can be estimated explicitly. It is shown that the obtained nonlinear estimator is unbiased and its variance is also derived. A condition is given when the proposed estimator is recommended instead of the ordinary least squares estimator.

  • 454.
    Wahl, Felix
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Explicit moments for a class of micro-models in non-life insurance2019Inngår i: Insurance, Mathematics & Economics, ISSN 0167-6687, E-ISSN 1873-5959, Vol. 89, s. 140-156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers properties of the micro-model analysed in Antonio and Plat (2014). The main results are analytical expressions for the moments of the outstanding claims payments subdivided into IBNR claims and individual RBNS claims. These moments are possible to compute explicitly using the discretisation scheme for estimation and simulation used in Antonio and Plat (2014) since the expressions then do not involve any integrals that, typically, would require numerical solutions. Other aspects of the model that are investigated are properties of the maximum likelihood estimators of the model parameters, such as bias and consistency, and a way of computing prediction uncertainty in terms of the mean squared error of prediction that does not require simulations. Moreover, a brief discussion is given on how to compute moments or risk-measures of the claims development result (CDR) using simulations, which based on the results of the present paper can be done without any nested simulations. Based on this it is straightforward to compute the one-year Solvency Capital Requirement, which corresponds to the 99.5% Value-at-Risk of the one-year CDR. A brief numerical illustration is used to show the theoretical performance of the maximum likelihood estimators of the parameters in the claims development process under this model using a realistic set-up based on the case-study of Antonio and Plat (2014). Additionally, the paper ends with a short numerical illustration discussing the model's robustness under violations of an independence assumption.

  • 455.
    Wahlund, Björn
    et al.
    Department of Clinical Neuroscience, Division of Psychiatry, Karolinska Institutet, Karolinska Hospital Huddinge, Stockholm, Sweden..
    Klonowski, Wlodzimierz
    Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland..
    Stepien, Paweł
    Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland..
    Stepien, Robert
    Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw..
    von Rosen, Tatjana
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    von Rosen, Dietrich
    The Department of Energy and Technology, SLU, Sweden.
    EEG data, fractal dimension and multivariate statistics2010Inngår i: Journal of Computer Science and Engineering, ISSN 2043-9091, Vol. 3, nr 1, s. 10-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper is to discuss the concept of Inverse Problem, i.e. how to obtain information via data about a complex mathematical model. We propose that by merging ideas from applied mathematics with ideas from multivariate statistical inference it is possible to find solutions or good approximation of many complex scientific problems.

  • 456.
    Wegmann, Bertil
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Comparison of Private and Common Values in Structural Second-Price AuctionsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    We compare the performance of the Gaussian second-price common value (CV) model in Wegmann and Villani (2011) to a comparable independent private value (IPV) version of that model. The two models are contrasted on a dataset from $1050$ Internet coin auctions at eBay. The models are evaluated along several dimensions, such as parameter inference, in-sample fit, and accuracy of out-of-sample predictive density forecasts. Both models fit the eBay data well with a slight edge for the more robust CV model. We do not find any evidence of a winner's curse effect in the eBay data, which speaks in favor of the IPV model. However, the optimal minimum bids in the CV model are clearly closer to the actual minimum bids in the eBay data than the optimal choice of no minimum bid in the IPV model. The IPV model predicts auction prices slightly better in most auctions, while the CV model is much better at predicting auction prices in more unusual auctions. The robustness of the CV model is also supported by a small simulation study, where the CV model performs relatively better on simulated data from the IPV model than the IPV model fitted to CV data.

  • 457.
    Wegmann, Bertil
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Inference in Structural Second-Price Auctions2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis is to develop efficient and practically useful Bayesian methods for statistical inference in structural second-price auctions. The models are applied to a carefully collected coin auction dataset with bids and auction-specific characteristics from one thousand Internet auctions on eBay. Bidders are assumed to be risk-neutral and symmetric, and compete for a single object using the same game-theoretic strategy. A key contribution in the thesis is the derivation of very accurate approximations of the otherwise intractable equilibrium bid functions under different model assumptions. These easily computed and numerically stable approximations are shown to be crucial for statistical inference, where the inverse bid functions typically needs to be evaluated several million times.

    In the first paper, the approximate bid is a linear function of a bidder's signal and a Gaussian common value model is estimated. We find that the publicly available book value and the condition of the auctioned object are important determinants of bidders' valuations, while eBay's detailed seller information is essentially ignored by the bidders. In the second paper, the Gaussian model in the first paper is contrasted to a Gamma model that allows intrinsically non-negative common values. The Gaussian model performs slightly better than the Gamma model on the eBay data, which we attribute to an almost normal or at least symmetrical distribution of valuations. The third paper compares the model in the first paper to a directly comparable model for private values. We find many interesting empirical regularities between the models, but no strong and consistent evidence in favor of one model over the other. In the last paper, we consider auctions with both private-value and common-value bidders. The equilibrium bid function is given as the solution to an ordinary differential equation, from which we derive an approximate inverse bid as an explicit function of a given bid. The paper proposes an elaborate model where the probability of being a common value bidder is a function of covariates at the auction level. The model is estimated by a Metropolis-within-Gibbs algorithm and the results point strongly to an active influx of both private-value and common-value bidders.

  • 458.
    Wegmann, Bertil
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Inference in Structural Second-Price Auctions with both Private-Value and Common-Value BiddersManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Auctions with asymmetric bidders have been actively studied in recent years. Tan and Xing (2011) show the existence of monotone pure-strategy equilibrium in auctions with both private-value and common-value bidders. The equilibrium bid function is given as the solution to an ordinary differential equation (ODE). We approximate the ODE and obtain a very accurate, approximate inverse bid as an explicit function of a given bid. This results in fast and numerically stable likelihood evaluations, which is an extremely valuable property for inference. We propose a model where the valuations of both common-value and private-value bidders are functions of covariates. The probability of being a common-value bidder is modeled by a logistic regression model with Bayesian variable selection. The model is estimated on a dataset of eBay coin auctions. We analyze the model using Bayesian methods implemented via a Metropolis-within-Gibbs algorithm. The posterior inference of the common-value part of the model is similar to the ones obtained from a model with only common-value bidders, whereas the private-value part of the model is more affected by the introduction of common-value bidders. There is on average a slightly larger probability for a bidder to be a common-value bidder, but this probability depends very little on the auction-specific covariates.

  • 459.
    Wegmann, Bertil
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Inference in Structural Second-Price Auctions with Gamma Distributed Common ValuesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Our paper explores possible limitations of the Gaussian model in Wegmann and Villani (2011) due to intrinsically non-negative values. The relative performance of the Gaussian model is compared to an extension of the Gamma model in Gordy (1998) within the symmetric second price common value model. A key feature in our approach is the derivation of an accurate approximation of the bid function for the Gamma model, which can be inverted and differentiated analytically. This is extremely valuable for fast and numerically stable evaluations of the likelihood function. The general MCMC algorithm in WV is utilized to estimate WV's eBay dataset from $1000$ auctions of U.S. proof coin sets, as well as simulated datasets from the Gamma model with different degrees of skewness in the value distribution. The Gaussian model fits the data slightly better than the Gamma model for the particular eBay dataset, which can be explained by the fairly symmetrical value distribution. The superiority of the Gamma to the Gaussian model is shown to increase for higher degrees of skewness in the simulated datasets.

  • 460.
    Wegmann, Bertil
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bid function approximations of second price common value auctions2007Rapport (Annet vitenskapelig)
    Abstract [en]

    Se RR 2007:4

  • 461.
    Wegmann, Bertil
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen. Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Villani, Mattias
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen. Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Inference and Variable Selection in Structural Second Price Common: Value Auctions2008Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Se internetadress: http://gauss.stat.su.se/rr/RR 2008_1.pdf

  • 462.
    Wegmann, Bertil
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Villani, Mattias
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Bayesian Inference in Structural Second-Price Common Value Auctions2011Inngår i: Journal of business & economic statistics, ISSN 0735-0015, E-ISSN 1537-2707, Vol. 29, nr 3, s. 382-396Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Structural econometric auction models with explicit game-theoretic modeling of bidding strategies have been quite a challenge from a methodological perspective, especially within the common value framework. We develop a Bayesian analysis of the hierarchical Gaussian common value model with stochastic entry introduced by Bajari and Hortacsu. A key component of our approach is an accurate and easily interpretable analytical approximation of the equilibrium bid function, resulting in a fast and numerically stable evaluation of the likelihood function. We extend the analysis to situations with positive valuations using a hierarchical gamma model. We use a Bayesian variable selection algorithm that simultaneously samples the posterior distribution of the model parameters and does inference on the choice of covariates. The methodology is applied to simulated data and to a newly collected dataset from eBay with bids and covariates from 1000 coin auctions. We demonstrate that the Bayesian algorithm is very efficient and that the approximation error in the bid function has virtually no effect on the model inference. Both models fit the data well, but the Gaussian model outperforms the gamma model in an out-of-sample forecasting evaluation of auction prices. This article has supplementary material online.

  • 463. Weidemann, Felix
    et al.
    Dehnert, Manuel
    Koch, Judith
    Wichmann, Ole
    Höhle, Michael
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen. Robert Koch Institute, Germany.
    Bayesian parameter inference for dynamic infectious disease modelling: Rotavirus in Germany2014Inngår i: Statistics in Medicine, ISSN 0277-6715, E-ISSN 1097-0258, Vol. 33, nr 9, s. 1580-1599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding infectious disease dynamics using epidemic models based on ordinary differential equations requires the calibration of model parameters from data. A commonly used approach in practice to simplify this task is to fix many parameters on the basis of expert or literature information. However, this not only leaves the corresponding uncertainty unexamined but often also leads to biased inference for the remaining parameters because of dependence structures inherent in any given model. In the present work, we develop a Bayesian inference framework that lessens the reliance on such external parameter quantifications by pursuing a more data-driven calibration approach. This includes a novel focus on residual autocorrelation combined with model averaging techniques in order to reduce these estimates’ dependence on the underlying model structure. We applied our methods to the modelling of age-stratified weekly rotavirus incidence data in Germany from 2001 to 2008 using a complex susceptible–infectious–susceptible-type model complemented by the stochastic reporting of new cases. As a result, we found the detection rate in the eastern federal states to be more than four times higher compared with that of the western federal states (19.0% vs 4.3%), and also the infectiousness of symptomatically infected individuals was estimated to be more than 10 times higher than that of asymptomatically infected individuals (95% credibility interval: 8.1–19.6). Not only do these findings give valuable epidemiological insight into the transmission processes, we were also able to  examine the considerable impact on the model-predicted transmission dynamics when fixing parameters beforehand.

  • 464. Welderufael, B. G.
    et al.
    De Koning, D. J.
    Fikse, W. F.
    Strandberg, E.
    Franzén, Jessica
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Christensen, O. F.
    Genetic evaluation of mastitis liability and recovery through longitudinal models of simulated SCC2013Inngår i: Book of Abstracts of the 64th Annual Meeting of the European Federation of Animal Science, Wageningen Academic Publishers, 2013, s. 522-522Konferansepaper (Fagfellevurdert)
  • 465. Welderufael, B. G.
    et al.
    de Koning, D. J.
    Janss, L.
    Franzén, Jessica
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Fikse, W. F.
    Longitudinal Analysis of Somatic Cell Count for Joint Genetic Evaluation of Mastitis and Recovery Liability2014Inngår i: Proceedings, 10th World Congress of Genetics Applied to Livestock Production, 2014, artikkel-id 095Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Better models of genetic evaluation for mastitis can be developed through longitudinal analysis of somatic cell count (SCC) which usually is used as a proxy for mastitis. Mastitis and recovery data with weekly observations of SCC were simulated for daughter groups of 60 and 240 per sire. Data were created to define cases: 1 if SCC was above a pre-specified boundary, else 0. A transition from below to above the boundary indicates probability to contract mastitis, and the other way indicates recovery. The MCMCglmm package was used to estimate breeding values. In the 60 daughters group, accuracies ranged from 0.53 to 0.54 for mastitis and 0.22 to 0.23 for recovery. Whereas, in the 240 daughters group accuracies ranged from 0.83 to 0.85 for mastitis and 0.57 to 0.65 for recovery. Reasonable accuracies can be achieved from SCC based estimates.

  • 466. Welderufael, B. G.
    et al.
    de Koning, D. J.
    Janss, L. L. G.
    Franzen, Jessica
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Fikse, W. F.
    Simultaneous genetic evaluation of simulated mastitis susceptibility and recovery ability using a bivariate threshold sire model2016Inngår i: Acta agriculturae Scandinavica. Section A, Animal science, ISSN 0906-4702, E-ISSN 1651-1972, Vol. 66, nr 3, s. 125-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to develop a new approach for joint genetic evaluation of mastitis and recovery. Two mastitis incidences (0.28 and 0.95) measured via somatic cell count and three between traits genetic correlations (0.0, 0.2, and -0.2) were simulated for daughter group sizes of 60 and 240. A transition model was applied to model transitions between healthy and disease state. The RJMC package in DMU was used to estimate (co)variances. Heritabilities were consistent with the simulated value (0.039) for susceptibility and a bit upward biased for recovery. Estimates of genetic correlations were -0.055, 0.205, and -0.192 for the simulated values of 0.0, 0.2, and -0.2, respectively. For daughter group size of 60, accuracies of sire EBV ranged from 0.56 to 0.69 for mastitis and from 0.26 to 0.48 for recovery. The study demonstrated that both traits can be modeled jointly and simulated correlations could be correctly reproduced.

  • 467. Welderufael, Berihu
    et al.
    De Koning, Dirk-Jan
    Fikse, Freddy
    Strandberg, Erling
    Franzén, Jessica
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Christensen, O. F.
    Genetic Evaluation of Mastistis Liability and Recovery through Longitudinal Models of SCC2013Konferansepaper (Fagfellevurdert)
  • 468. Welderufael, Berihu
    et al.
    Fikse, Freddy
    Franzén, Jessica
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Strandberg, Erling
    Christensen, O. F.
    De Koning, Dirk-Jan
    Genetic Evaluation of Getting and Recovering from an Intramammary Infection through Longitudinal Models of Somatic Cell Count2013Konferansepaper (Fagfellevurdert)
  • 469. Welsh, Alan H.
    et al.
    Hedlin, Dan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Šova, Markus G.
    The Stabilisation of Model Parameter Estimates from Repeated Surveys with Rare Observations2013Inngår i: Australian & New Zeeland Journal of Statistics, ISSN 1467-842X, Vol. 55, nr 4, s. 471-491Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In many surveys, the domains of study are small and the samples that carry information on a domain can be very small indeed. If the survey is conducted repeatedly there is often a high degree of overlap in samples over time. We show how to use the richness of information over time to compensate for the paucity of cross-sectional information. We propose a model-based estimator of the population total based on stabilised parameter estimates that combine information from different survey periods that are adjacent in time.  The motivating example for this research has been the ProdCom survey as implemented in the UK.

  • 470.
    Wiese, Linda
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Stratification, Sampling and Estimation: Finding the best design for the Swedish Investment Survey2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this thesis, different methods are used to investigate the best design for the Swedish Investment Survey. The methods used today are stratify on number of employees, Neyman-allocation, STSRS-sampling and HT-estimation. The alternative methods in this thesis are stratify on turnover, -sampling and GREG-estimation. These methods are combined into eight combinations and tested on the enterprises and their investments in the Swedish energy domains. The conclusion is that changing the design to stratify on turnover, -sampling and GREG-estimation will provide a smaller standard deviation in most of the energy domains.

  • 471.
    Wretman, Jan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Unbiased Nonlinear Estimators of a Finite Population Total: Do They Exist?2007Inngår i: Statistics in Transition: New Series, ISSN 1234-7655, Vol. 8, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unbiased nonlinear estimators of a finite population total exist if and only if the sampling design is a nonunicluster design with strictly positive inclusion probabilities.

  • 472.
    Wänström, Linda
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Intelligence and models for cognitive development2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This dissertation focuses on cognitive development. In papers I and II, I study a special model, the second order latent growth curve model, that can be used to study cognitive development. Algebraic expressions for the variance of the estimation of slope differences are given. They may be used to calculate the sample sizes needed to detect slope differences between groups. Illustrations of the formulas indicate that sample sizes decrease with effect size, number of indicators and their reliabilities, frequency of observation and duration of the study. In addition, observations near the beginning and end are more important than observations in the middle, and needed sample sizes increase with attrition. Smaller sample sizes are also needed in studies in which baseline levels between groups may be assumed equal, and correlations between factors can either increase or decrease needed sample size.

    Papers III and IV address different aspects of cognitive development. The Flynn effect refers to the observed fact that IQ scores increase over time. In Paper III, we suggest outlining the boundaries within which this effect occurs prior to investigating possible causes. We observe an effect in a test in a large American dataset. This dataset contains information that can be used to outline these boundaries as well as to search for possible causes. Paper IV addresses the observed correlation between sibship size or birth order and cognitive ability. If sibship size negatively affects cognitive ability in children, this should be detected studying children’s cognitive development prior to, and after, the birth of a sibling. Using longitudinal multilevel analyses on a large sample of American children from ages five to fourteen, differences between children of different sibship sizes are noted. Their cognitive abilities do not change following the birth of a sibling however.

  • 473.
    Wänström, Linda
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Fackle-Fornius, Ellinor
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Minimax optimality and the trinomial spike model2011Rapport (Annet vitenskapelig)
  • 474. Zhou, Hong-Wei
    et al.
    Zhou, Fang
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen. Capital University of Economics and Business, China.
    A Meta-analysis on the clinical efficacy and safety of optic capture in pediatric cataract surgery2016Inngår i: International Journal of Ophthalmology, ISSN 2222-3959, Vol. 9, nr 4, s. 590-596Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: To evaluate the clinical efficacy and safety of optic capture in pediatric cataract surgery. METHODS: Searches of peer-reviewed literature were conducted in PubMed, Embase and the Cochrane Library. The search terms were optic capture and cataract. The retrieval period ended in December 2014. Relevant randomized controlled trials (RCTs), case - control studies and cohort studies were included. Meta-analyses were performed. Pooled weighted mean differences and risk ratios with 95% confidence intervals were estimated. RESULTS: Ten studies involving 282 eyes were included, 5 of which were RCTs involving 194 eyes. The application of optic capture significantly reduced both opacification of the visual axis (RR: 0.12; 95% CI: 0.02 to 0.85; P=0.03) and occurrence of geometric decentration (RR: 0.09; 95% CI: 0.02 to 0.46; P=0.004). But it did not significantly affect best corrected visual acuity (BCVA) (WMD: -0.01; 95% CI: -0.07 to 0.05; P =0.75) and influence the occurrence of posterior synechia (RR: 1.53; 95% CI: 0.84 to 2.77; P=0.17). Deposits in the anterior intraocular lens were significantly increased in the optic capture group early after surgery (RR: 1.40; 95% CI: 1.05 to 1.86; P =0.02) and at the last follow-up (RR: 2.30; 95% CI: 1.08 to 4.92; P=0.03). The quality of the evidence was assessed as high. CONCLUSION: The application of optic capture significantly reduces opacification of visual axis and occurrence of geometric decentration but do not significantly improve BCVA with notable safety.

  • 475. Öhrvik, John
    Robusteffektiv lägesestimation1982Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis considers an adaptive estimator of location having the property that it is asymptotically normally distributed for a family of symmetric distributions constrained only by regularity conditions. The estimator is shown to possess good efficiency robustness properties, both asymptotically and for small samples. It is also shown that a suitably studentized version of the estimator is approximately t-distributed for small and moderate sample sizes. This makes it possible to construct confidence intervals and tests for the location parameter. The small sample properties are investigated with the aid of Monte Carlo experiments. Special care has been taken to reduce the uncertainty in the results of these experiments.

  • 476.
    Öller, Lars-Erik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Book review 2008Inngår i: International Journal of Forecasting, ISSN 0169-2070, Vol. 24, nr 1, s. 179-183Artikkel i tidsskrift (Fagfellevurdert)
78910 451 - 476 of 476
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