Re: Stats question: Comparison of the same individuals during two exposure times
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You have been warned!
On Tue, Jul 17, 2012 at 2:10 AM, natalie.vanzuydam <[hidden email]>wrote:
> I'm hoping that someone will be able to help. I would like to compare how
> covariates associate with the risk of a binary outcome during two periods.
> Period 1 will be non-exposure to a treatment and period 2 will be exposure
> to a treatment. The same individuals will be examined in each group but I
> want to be able to compare the association of certain covariates between
> two groups to see if there is a treatment interaction. I've looked at
> case-crossover designs and time series analysis and don't think that they
> are suitable. The cohort has longitudinal data so individuals will go onto
> treatment at different times and the effect of the treatment needs to be
> administered for a while before it has an effect. The reason why I cannot
> just go ahead with an exposed vs unexposed design is that most individuals
> in the cohort end up on the treatment eventually and the unexposed group is
> very small and lacks power for a meaningful comparison.
> Is there anyway to compare the same individuals during different exposure
> times and to look at the effect of different covariates under the exposed
> and unexposed conditions?
> Thanks for you help,
> Natalie Van Zuydam
> PhD Student
> University of Dundee
> [hidden email] > --
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