scholarly journals A Semiparametric Bayesian Approach to Dropout in Longitudinal Studies With Auxiliary Covariates

2019 ◽  
Vol 29 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Tianjian Zhou ◽  
Michael J. Daniels ◽  
Peter Müller
2009 ◽  
Vol 2009 ◽  
pp. 1-24 ◽  
Author(s):  
Clelia Di Serio ◽  
Claudia Lamina

Modelling data from Multiple Sclerosis longitudinal studies is a challenging topic since the phenotype of interest is typically ordinal; time intervals between two consecutive measurements are nonconstant and they can vary among individuals. Due to these unobservable sources of heterogeneity statistical models for analysis of Multiple Sclerosis severity evolve as a difficult feature. A few proposals have been provided in the biostatistical literature (Heijtan (1991); Albert, (1994)) to address the issue of investigating Multiple Sclerosis course. In this paper Bayesian P-Splines (Brezger and Lang, (2006); Fahrmeir and Lang (2001)) are indicated as an appropriate tool since they account for nonlinear smooth effects of covariates on the change in Multiple Sclerosis disability. By means of Bayesian P-Spline model we investigate both the randomness affecting Multiple Sclerosis data as well as the ordinal nature of the response variable.


2011 ◽  
Vol 70 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Ben (C) Fletcher ◽  
Jill Hanson ◽  
Nadine Page ◽  
Karen Pine

Two 3-month longitudinal studies examined weight loss following a 1-month behavioral intervention (FIT-DSD) focusing on increasing participants’ behavioral flexibility and breaking daily habits. The goal was to break the distal habits hypothesized as playing a role in unhealthy dietary and activity behaviors. The FIT-DSD intervention required participants to do something different each day and to engage in novel weekly activities to expand their behavioral repertoire. These activities were not food- or exercise-related. In Study 1, the FIT-DSD program was compared with a control condition where participants engaged in daily tasks not expected to influence behavioral flexibility. Study 2 used an active or quasicontrol group in which half the participants were also on food diets. Measures in both studies were taken pre-, post-, and post-postintervention. In Study 1, FIT-DSD participants showed greater weight loss that continued post-postintervention. In Study 2, all participants on the FIT-DSD program lost weight, weight loss continued post-postintervention, and participants who were also dieting lost no additional weight. A dose relationship was observed between increases in behavioral flexibility scores and weight loss, and this relationship was mediated by calorie intake. Corresponding reductions in BMI were also present. Increasing behavioral flexibility may be an effective approach for tackling obesity and also provides affective and potential life-skill benefits.


2018 ◽  
Vol 144 (4) ◽  
pp. 426-451 ◽  
Author(s):  
Kevin A. Hoff ◽  
Daniel A. Briley ◽  
Colin J. M. Wee ◽  
James Rounds

2018 ◽  
Vol 144 (10) ◽  
pp. 1045-1080 ◽  
Author(s):  
Ulrich Orth ◽  
Ruth Yasemin Erol ◽  
Eva C. Luciano

2008 ◽  
Author(s):  
Philip M. Sirinides ◽  
Clare Waterman ◽  
Lauren E. Angelo ◽  
Heather P. Warley ◽  
Paula A. McDermott

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