I disagree here on two standard grounds.
* OLS is all too likely to produce predictions
outside [0,1].
* To degrade an approximately
continuous variable by categorising it in this
way is just throwing away information in the
data.
Other postings pointed to possible analyses.
Nick
n.j.cox@durham.ac.uk
Carter Rees, M.A.
> I would think that if it is a ratio variable an OLS
> regression would suffice. OLS is pretty robust when it comes
> to its assumptions so the S shape may not be a problem.
> However, your definition of "somewhat" S shaped has to be
> considered. If it is truly an S-shaped (binomial)
> distribution you should check to see if you can identify a
> logical cut point and turn your DV into a categorical 0/1
> variable and run a logistic regression. If not a simple 0/1,
> maybe multinomial or ordinal regression would be the way to
> go. In any event, if you do decide on a categorical DV check
> out Scott Long's Regression Models for Categorical Dependent
> Variables Using Stata.
________________________________________
Eugene Kang
> I am using STATA 8 to analyze a model with a ratio DV ranging
> from 0 to 1. The distribution of this DV is somewhat
> S-shaped. I was wondering if someone could point me to the
> correct statistical analysis to use (I can read the STATA
> manual and other books from there on).
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