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Re: st: stepwise et al


From   "b.qureishi" <b.qureishi@ucl.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: stepwise et al
Date   Mon, 27 Aug 2007 20:33:38 +0100

Thanks for the prompt response Phil.
I was using qregs to control against outliers. Subsequently, due to the lack of
observations I was not getting any t-values. Ive manually adjusted my outliers
and am now using standard regs as oppose to the former.

Kind Regards,
Bilal
Quoting Phil Schumm <pschumm@uchicago.edu>:


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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