[Statlist] Seminar ueber Statistik

[Christina Kuenzli]

                       ETH and University of Zurich 
      Proff. A.D. Barbour -- P. Buehlmann -- F. Hampel -- H.R. Kuensch 

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           We are pleased to announce the following talk
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Friday, January 14, 2005, 15.15 h, LEO C 15

        Modeling Neuromotor Ratings with Floor Effects

        Valentin Rousson, Biostatistics, University of Zurich

Associated movements (AMs) are a classical diagnostic tool to assess 
differences between normal children and children with some motor 
dysfunction. This talk will present a methodology to produce age- and 
gender-dependent reference-curves for AMs of normal children, for various 
tasks of a test battery. Data available consist of separate ratings of 
duration and extent of AMs, which are ordinal quantities with few levels. 
Another problem are severe age- and gender-dependent floor-effects (as 
well as some ceiling-effects), leaving little information for analysis at 
older ages. To get a better scale, we combined the two ordinal ratings 
into one meaningful and quasi-continuous quantity referred to as intensity 
of AMs. In order to solve problems due to floor-effects, ceiling-effects 
and discreteness, we assumed left-censored, right-censored and 
interval-censored values, respectively. We considered hence a censored 
regression problem and postulated a truncated normal distribution for the 
non-censored values (after an appropriate transformation of the data). 
Using Tanner and Wei's poor man's data augmentation algorithm, together 
with the technique of linear mixed effects modeling, useful 
reference-curves could be produced. We could therefore calculate 
individual age- and gender-standardized values, which puts us in a 
position to investigate numerous interesting scientific questions.

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          The next seminar is scheduled for January 21th, 2005. 
                          More information soon.
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Overview maps of ETH : http://www.ethz.ch/search/orientation_en.asp
________________________________________________________
Christina Kuenzli            <kuenzli at stat.math.ethz.ch>
Seminar fuer Statistik      
Leonhardstr. 27,  LEO D11          phone: +41 1 632 3438         
ETH-Zentrum,                       fax  : +41 1 632 1228 
CH-8092 Zurich, Switzerland        http://stat.ethz.ch/~