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Re: st: stepwise et al


From   Phil Schumm <pschumm@uchicago.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: stepwise et al
Date   Mon, 27 Aug 2007 13:37:50 -0500

On Aug 27, 2007, at 10:52 AM, b.qureishi wrote:
Instead a T statistic, I would get "." Does anyone know why this is happening?

Presumably because Stata is unable to calculate the corresponding standard error(s) in this case. This is often the result of some collinearity among your covariates, or some lack of variation in your outcome, or a mixture of both. Also, pay attention to your estimation sample (i.e., the set of observations being used to estimate the model); often this gets reduced to a subset of the entire sample for some reason (e.g., missing data), and that's what leads to the problem.


-- Phil

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