نتایج جستجو برای: longitudinal data

تعداد نتایج: 2500390  

2003
Tom A.B. Snijders

This chapter treats statistical methods for network evolution. It is argued that it is most fruitful to consider models where network evolution is represented as the result of many (usually non-observed) small changes occurring between the consecutively observed networks. Accordingly, the focus is on models where a continuous-time network evolution is assumed although the observations are made ...

2004
ELJA ARJAS JAN PARNER

This paper reviews some of the key statistical ideas that are encountered when trying to find empirical support to causal interpretations and conclusions, by applying statistical methods on experimental or observational longitudinal data. In such data, typically a collection of individuals are followed over time, then each one has registered a sequence of covariate measurements along with value...

افتخاری, سمانه, حسینی, مصطفی, رضا نژاد اصل, پریسا, محمودی, محمود, نوری, کرامت اله,

  Background & Objectives : Longitudinal studies are used in many psychiatric researches to evaluate the effectiveness of treatment. The main characteristic of longitudinal studies is repeated measurements of the patients over time. Since observations from the same patient are not independent from each other, especial statistical methods must be used for analyzing the data. Missing data is an i...

2004
ROGER KOENKER Steve Portnoy Xuming He Gib Bassett Carlos Lamarche

The penalized least squares interpretation of the classical random effects estimator suggests a possible way forward for quantile regression models with a large number of “fixed effects”. The introduction of a large number of individual fixed effects can significantly inflate the variability of estimates of other covariate effects. Regularization, or shrinkage of these individual effects toward...

Journal: :Information processing in medical imaging : proceedings of the ... conference 2015
Yi Hong Nikhil Singh Roland Kwitt Marc Niethammer

We consider how to test for group differences of shapes given longitudinal data. In particular, we are interested in differences of longitudinal models of each group's subjects. We introduce a generalization of principal geodesic analysis to the tangent bundle of a shape space. This allows the estimation of the variance and principal directions of the distribution of trajectories that summarize...

2017
D. M. Farewell C. Huang V. Didelez

Likelihood factors that can be disregarded for inference are termed ignorable. We demonstrate that close ties exist between ignorability and identification of causal effects by covariate adjustment. A graphical condition, stability, plays a role analogous to that of missingness at random, but is applicable to general longitudinal data. Our formulation of ignorability does not depend on any noti...

Journal: :Psychometrika 2007
Kees van Montfort

The book Models for intensive longitudinal data is an edited volume consisting of eleven chapters by 23 authors. These chapters are separate contributions without links to the other chapters. To escape the impression that this is a fragmented book, the editors Theodore A. Walls and Joseph L. Schafer start with a twelve-page Introduction. This Introduction gives an extensive overview of the chap...

2015
Mary E. Thompson

Common features of longitudinal surveys are complex sampling designs, which must be maintained and extended over time; measurement errors, including memory errors; panel conditioning or time-in-sample effects; and dropout or attrition. In the analysis of longitudinal survey data, both the theory of complex samples and the theory of longitudinal data analysis must be combined. This article revie...

Journal: :CoRR 2017
Louis Falissard Guy Fagherazzi Newton Howard Bruno Falissard

Deep neural networks are a family of computational models that have led to a dramatical improvement of the state of the art in several domains such as image, voice or text analysis. These methods provide a framework to model complex, non-linear interactions in large datasets, and are naturally suited to the analysis of hierarchical data such as, for instance, longitudinal data with the use of r...

2011
Vadim Zipunnikov Sonja Greven Brian Caffo Daniel S. Reich Ciprian Crainiceanu

We develop a flexible framework for modeling high-dimensional functional and imaging data observed longitudinally. The approach decomposes the observed variability of high-dimensional observations measured at multiple visits into three additive components: a subject-specific functional random intercept that quantifies the cross-sectional variability, a subject-specific functional slope that qua...

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