Dear All,
This question has been asked once before but went unanswered. I am
analysing twin pairs discordant (one has one has not a diagnosis) and
concordant (both have) for a psychiatric disorder - as well as control
pairs. The sample is - mixed identical and non identical.
The problem is: most statistical tests assume independence of observation,
but twins are clearly not independent. Depending on the model, this results
in a violation of such assumptions between and within groups. I'd like to
know if there is any way of addressing this issue within SPM?
Many Thanks
Fergus
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