Re: st: Thread-Index: Ac2zpwBrnny9GG5FQQ6Vz7stZfQOCw==

[Richard Goldstein <richgold@ix.netcom.com>]

the reason for the error message is that you need to include a comma
prior to the "xb": predict xb1, xb

Rich

On 10/26/12 2:25 PM, Amal Khanolkar wrote:
> Hi,
> 
> I tried running the lroc command following my logistic regression as follows:
> 
> xi: logistic moth_wtgain_under i.mom_race2 age_mom sexx if parity!=. & gestwk_cat!=. & cigs_befx!=. & cigs_1stx!=. & cigs_2ndx!=. & cigs_3rdx!=. & gestdb!=. & gesthy!=. & ht_cm!=. & plural==1 & edu_mom!=. & marriedxx!=.
> lroc, nograph
> predict xb1 xb
> 
> Based on an example I saw online in the Stata manual, I use 'predict' as above to produce a linear predictor model. I do the same for another 4 models, i.e.
> 
> logistic model 2
> lroc, nograph 
> predict xb2 xb
> 
> logistic model 3
> lroc, nograph 
> predict xb3 xb
> 
> ..... and so on. 
> 
> All four logistic models have the same outcomes, but different explanatory variables. My aim is use the roccomp command as follows to be able to compare all 4 models easily:
> 
> roccomp hon xb1 xb2 xb3 xb4, graph summary
> 
> 
> 1. I get an error message after running the first 'predict xb1 xb' above.  ('too many variable specified'). I didn't think this would be a problem. Is there any way I can get around this, or do I have to r educe the number of covariates specified in my logistic model?
> 
> 2. Or is there a better approach?
> 
> Thanks!
> 
> /Amal.
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