Statistical Modelling 1 (2001), 125–142
A Local Influence Approach
to Sensitivity Analysis of Incomplete Longitudinal Ordinal Data
Kristel Van Steen
Biostatistics, Center for Statistics, Limburgs Universitair Centrum
Universitaire Campus, B-3590 Diepenbeek, Belgium
eMail:
kristel.vansteen@luc.ac.be
Geert Molenberghs
Biostatistics, Center for Statistics, Limburgs Universitair Centrum
Universitaire Campus, B-3590 Diepenbeek, Belgium
tel: +32 11 26 8238, fax: +32 11 26 8299,
eMail:
geert.molenberghs@luc.ac.be
Geert Verbeke
Biostatistical Centre, Katholieke Universiteit Leuven, Kapucijnenvoer
B-3000 Leuven, Belgium
eMail:
geert.verbeke@med.kuleuven.ac.be
Herbert Thijs
Biostatistics, Center for Statistics, Limburgs Universitair Centrum,
Universitaire Campus, B-3590 Diepenbeek, Belgium
Abstract:
One of the major concerns
when analyzing incomplete longitudinal
data is the fact that models necessarily rest on strong assumptions,
unverifiable from the data (Glynn, Laird and Rubin 1986). In
response to these concerns, there is growing awareness of the
usefulness of sensitivity analysis. In this paper we will focus on
repeated ordinal data. Specifically, we implement a formal approach
to such a sensitivity assessment, based on local influence (Cook, 1986),
in the presence of multivariate categorical data. We explore the
influence of perturbing a MAR dropout model in the direction of
non-random dropout, and apply the proposed method to data from a
longitudinal multicentre psychiatric study.
Keywords:
Influence Analysis;
Incomplete Data;
Multivariate Dale Model;
Missing Data;
Perturbation Scheme;
Sensitivity Analysis.
Downloads:
Data sets and programs:
The zipped archive
contains the following files:
- an MS-Word document with guidelines to use the programs: Guidelines.doc
- the specific Gauss code used to generate the results of the article:
main.bat, sex.bat, age.bat, mismod.bat
- Ndale.hlp
- a zipped file containing the relevant data files: myobjects.zip
- a zipped file containing Gauss libraries: gausslibs.zip
- a zipped file containing Dale programs that are referred to by the main
programs: dale.zip
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