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Re: st: Bug in margins
From
roland andersson <[email protected]>
To
[email protected]
Subject
Re: st: Bug in margins
Date
Fri, 30 Aug 2013 18:22:36 +0200
Richard
Sorry for the i. which should not have been in the first model.
Joe
I found it on page 1063. I think I am not the only one having this
problem. I have googled and found many similar postings but I have not
found the need for the i. in the model previously. If it is not a bug
it is a nuisance which could be better done or the error text could
give a hint.
Thank you.
Roland
2013/8/30 Joe Canner <[email protected]>:
> Roland,
>
> The requirement that the original model be specified including "i." is also buried deep in the PDF documentation for -margins- (page 1063 of r.pdf). The original model runs fine because binary variables don't need the "i.", but for whatever reason -margins- requires it.
>
> Joe Canner
> Johns Hopkins University School of Medicine
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Richard Williams
> Sent: Friday, August 30, 2013 12:51 PM
> To: [email protected]; [email protected]
> Subject: Re: st: Bug in margins
>
> 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
> OFFICE: (574)631-6668, (574)631-6463
> HOME: (574)289-5227
> EMAIL: [email protected]
> WWW: http://www.nd.edu/~rwilliam
>
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>
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