Research Report: Recent submissions
Visas titlar 101-120 av 130
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Preliminary testing in a class of simple non-linear mixed models to improve estimation accuracy
(2003-09-02)In applied research hypothetical information about the parameters in a stochastic model sometimes can be generated from theory or previous studies. Replacing unknown parameters by constants might increase the estimation ... -
Maximum Likelihood Ratio based small-sample tests for random coefficients in linear regression
(2003-08-01)Two small-sample tests for random coefficients in linear regression are derived from the Maximum Likelihood Ratio. The first test has previously been proposed for testing equality of fixed effects, but is here shown to be ... -
Simple conservative confidence intervals for comparing matched proportions
(University of Gothenburg, 2011-01-01)Unconditional confidence intervals (CIs) for the difference between marginal proportions in matched pairs data have essentially been based on improvements of Wald’s large-sample statistic. The latter are approximate and ... -
A CUSUM PROCEDURE FOR DETECTION OF OUTBREAKS IN POISSON DISTRIBUTED MEDICAL HEALTH EVENTS
(University of Gothenburg, 2010-11-02)CUSUM procedures which are based on standardized statistics are often supposed to have expectation zero and being normally distributed. If these conditions are not satisfied it can have serious consequences on the determination ... -
Relative Efficiency of a Quantile Method for Estimating Parameters in Censored Two-Parameter Weibull Distributions
(University of Gothenburg, 2010-11-01)In simulation studies the computer time can be much reduced by using censoring. Here a simple method based on quantiles (Q method) is compared with the Maximum Likelihood (ML) method when estimating the parameters in ... -
Multivariate outbreak detection
(University of Gothenburg, 2010)On-line monitoring is needed to detect outbreaks of diseases like influenza. Surveillance is also needed for other kinds of outbreaks, in the sense of an increasing expected value after a constant period. Information on ... -
Modelling the spatial patterns of influenza incidence in Sweden
(University of Gothenburg, 2010)Information about the spatial spread of epidemics can be useful for many purposes. The spatial aspect of Swedish influenza data was analyzed with the main aim of finding patterns that could be useful for statistical ... -
Sufficient reduction in multivariate surveillance
(2009-08-31)The relation between change points in multivariate surveillance is important but seldom considered. The sufficiency principle is here used to clarify the structure of some problems, to find efficient methods, and to determine ... -
Evaluation of multivariate surveillance
(2009-05-15)Multivariate surveillance is of interest in many areas such as industrial production, bioterrorism detection, spatial surveillance, and financial transaction strategies. Some of the suggested approaches to multivariate ... -
Statistiska varningssystem för hälsorisker
(2009-02-17)Varningssystem behövs t.ex. vid intensivövervakning, smittskydd, miljörisker och kvalitetskontroll av vården. Statistiska varningssystem signalerar när det skett en väsentlig ändring och man vet vilka egenskaper systemet ... -
Explorative analysis of spatial patterns of influenza incidences in Sweden 1999—2008
(2009-02-17)Information about the spatial spread of epidemics can be useful for many purposes. In this paper, the spatial aspect of Swedish influenza data is analyzed with the main aim of finding patterns that could be useful for ... -
On statistical surveillance of the performance of fund managers
(2009-02-17)The aim of this report is to describe if and how statistical surveillance methods for monitoring of the performance of fund managers has been used. Statistical surveillance is a methodology for on-line monitoring, in which ... -
Hotelling´s T2 Method in Multivariate On-Line Surveillance. On the Delay of an Alarm
(2008-11-28)A system for detecting changes in an on-going process is needed in many situations. On-line monitoring (surveillance) is used in early detection of disease outbreaks, of patients at risk and of financial instability. By ... -
Semiparametric surveillance of outbreaks
(2008-07-02)The detection of a change from a constant level to a monotonically increasing (or decreasing) regression is of special interest for the detection of outbreaks of, for example, epidemics. A maximum likelihood ratio statistic ... -
Semiparametric estimation of outbreak regression
(2008-07-02)A regression may be constant for small values of the independent variable (for example time), but then a monotonic increase starts. Such an “outbreak” regression is of interest for example in the study of the outbreak of ... -
When does Heckman’s two-step procedure for censored data work and when does it not?
(2008-02-22)Heckman’s two-step procedure (Heckit) for estimating the parameters in linear models from censored data is frequently used by econometricians, despite of the fact that earlier studies cast doubt on the procedure. In this ... -
Introduction to financial surveillance
(2008-02-08) -
On curve estimation under order restrictions
(2008-02-04)Robust regression is of interest in many problems where assumptions of a parametric function may be inadequate. In this thesis, we study regression problems where the assumptions concern only whether the curve is increasing ... -
Unimodal regression in the two-parameter exponential family with constant or known dispersion parameter
(2008-02-04)In this paper we discuss statistical methods for curve-estimation under the assumption of unimodality for variables with distributions belonging to the two-parameter exponential family with known or constant dispersion ... -
Explorative analysis of spatial aspects on the Swedish influenza data
(2007-12-20)The spatial aspects on the Swedish influenza data are analyzed. During the influenza period, reports on laboratory diagnosed cases and influenza-like-illness are obtained from viral and microbiological laboratories and ...