Dear Statalist
I have a case control study in which cases were inpatient suicides
and eligible controls were alive and in inpatient care on the index
date (i.e. the date of death of the corresponding case). There is no
matching for age, sex, diagnosis, or any other explanatory variable.
I'd greatly appreciate advice on the following two issues:
1) Is this a matched design, or does the single criterion for
selection of controls (i.e. alive on index date) simply constitue
sampling from the risk set (as in Clayton & Hills, 1993)? Therefore
should I analyse the data using conditional logistic regression or
just use the simple 'logit' / 'logistic' commands?
2) If conditional logistic regression is required, how can I perform a
sample size calculation that accounts for matching? (I'd like to
know the answer to this anyway, please, regardless of your
answers to Qu.1). The 'sampsi' command doesn't appear to provide
any options for sample size calculations with matched designs.
Thanks
Roger Webb
School of Psychiatry & Behavioural Sciences
Manchester (UK)
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