Re: st: Bug in margins

[Richard Williams <richardwilliams.ndu@gmail.com>]

First off, your 2 logistic commands look identical to me. I'm 
guessing that when you ran it the first time and got the error, you 
did not have the i.

Assuming that is the case, this is no error. The i. tells Stata that 
the variable is categorical rather than continuous. See the help for 
margins. Or, for some highlights on the margins command, see

http://www3.nd.edu/~rwilliam/stats/Margins01.pdf



At 10:39 AM 8/30/2013, roland andersson wrote:
> I am analysing a logistic regression model, binary outcome. I want to
> analyse the adjusted proportion of the outcome for a binary (0/1)
> covariate.
>
> I run the logistic model followed by margins
> . logistic dod30dgr  i.lapscopiintent alder aldersq........
> . margins lapscopiintent
>
> I get an error
> 'lapscopiintent' not found in list of covariates
> r(322);
>
> If I put i. before the binary variable I am interested in
>
> . logistic dod30dgr  i.lapscopiintent alder aldersq................
> . margins lapscopiintent
>
> Predictive margins Number of obs   = 166811
> Model VCE    : OIM
>
> Expression   : Pr(dod30dgr), predict()
>
> Delta-method
> Margin   Std. Err. z P>z [95% Conf. Interval]
> lapscopiin~t
> 0     .0015466   .0000985 15.70 0.000 .0013535 .0017397
> 1     .0011487   .0002518 4.56 0.000 .0006552 .0016421
>
> I assume this is a bug?
>
> Roland Andersson
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Richard Williams, Notre Dame Dept of Sociology
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