On 11/27/2009 Michael Crain <[email protected]> wrote:
>I have a data set of 35 observations with the predictor variable (x1)
>using the Likert scale and y = 0 or 1.
>I run -logit- and -logistic- (Stata v 10) and get a result that says:
>
>note: outcome = x1> 3 predicts data perfectly except for
> x1 == 3 subsample:
> x1 dropped and 28 obs not used
>
>-logit- is dropping 28 of the 35 observations and is using only 7 observations
>for the logit model but I don't understand the theoretical reason for doing so.
>...
Michael-
Your data has partial separation. I recommend the -firthlogit- command
by Joseph Coveney. It will give you an estimate for your predictor x1. To
get the program type -findit firthlogit-.
Phil
--
Phil Ender
Statistical Consulting Group
UCLA Academic Technology Services
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