Re: longitudinal binary data question

Posted by Kornbrot, Diana on Mar 31, 2007; 9:01am
URL: http://spssx-discussion.165.s1.nabble.com/longitudinal-binary-data-question-tp1074800p1074805.html

As far as I can make out mixed is only for continuous data, won¹t do binary
or ordinal
This is very serious omission in SPSS.

Try putting data in as for mixed with time as a categorical variable and
repeat subject numbers for each  time poitn
The run binary logit with both participant and time point as factors
Not ideal, as assumes ONLY binomial variance, not participant variance. So
you may get spurious significant effects as variance estimate is too small
BUT
If you save probabilities for each participant and then convert them back to
logits, you can estimate the extra binomial variance

Realy clutsy, I tried telling SPSS at their UL user conference, fell on deaf
ears
Best

diana


On 30/3/07 22:12, "S Crawford" <[hidden email]> wrote:

> Hi everyone,
>
> I am trying to find out if SPSS can analyze longitudinal binary data.  We
> have two patient groups, and we are following them over 4 time points - and
> the physician seeing each subject codes whether or not they are symptomatic
> (yes or no) at each time point.  I know I can't do repeated measures ANOVA
> on this because the data are binary.  Would this work in mixed models in
> SPSS? I've tried clicking on mixed models, but I'm getting lost.
>
> Any helpful hints greatly appreciated.
>
> Thanks!
>
> Susan Thomson, M.Sc.
> Research Coordinator
> Alberta Children's Hospital
>
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Professor Diana Kornbrot
Evaluation Co-ordinator, Blended Learning Unit
University of Hertfordshire
College Lane, Hatfield, Hertfordshire AL10 9AB, UK

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