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Re: st: Interaction term in logistic regression


From   Ashish Gupta <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: Interaction term in logistic regression
Date   Tue, 22 Apr 2014 13:54:48 +0530

Thanks Martin I have mistakenly placed dependent variable after the
independent variable.In addition,i would like to inquire whether I can
use spline models for separate age groups( binary 1/0 for each
age-group).Since I am looking for the odds of mortality across age
groups.
Best regards
Ashish Kumar Gupta
Senior Research Fellow (Population Studies)
International Institute for Population Sciences (IIPS), Govandi
Station Road, Deonar,
Mumbai-400 088, INDIA
Mobile No.: +91 9967106908





On Tue, Apr 22, 2014 at 12:50 PM, Maarten Buis <[email protected]> wrote:
> I can see a couple of problems:
>
> 1) For a logistic regression the dependent variable needs to be the
> first variable mentioned in the variable list and it should not
> contain a prefix (i.).
>
> 2) The -xi:- prefix is outdated, you should use the factor variable
> notation instead whenever possible, see -help fvvarlist-.
>
> 3) I would consider using a linear spline (1st order spline) instead
> of age in categories (0th order spline). The linear spline is a more
> flexible than age categories, but is still easily interpretable. For
> even more flexible but still interpretable effects you can look at:
> Roger B. Newson (2012) "Sensible parameters for univariate and
> multivariate splines" The Stata Journal, 12(3): 479-504.
>
> 4) If you use income as a variable, then I would call it income and
> not economic status. The latter could be interpreted as more general,
> for example it could wealth, which you did not do in your model.
>
> -- Maarten
>
>
> On Tue, Apr 22, 2014 at 7:12 AM, Ashish Gupta <[email protected]> wrote:
>> I am planning to employ  logistic regression with interactions to see
>> the effect of socio-economic characteristics on age-specific
>> mortality.I would like to know that how one can include interaction
>> term (Age versus economic status) in adjusted as well as unadjusted
>> model.
>> Example of the model-
>> xi : logit i. race  i. age_group i. income i.place_res  i.age_group ##i.income
>>
>> Any response will be appreciated.
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
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>> *   http://www.ats.ucla.edu/stat/stata/
>
>
>
> --
> ---------------------------------
> Maarten L. Buis
> WZB
> Reichpietschufer 50
> 10785 Berlin
> Germany
>
> http://www.maartenbuis.nl
> ---------------------------------
> *
> *   For searches and help try:
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> *   http://www.stata.com/support/faqs/resources/statalist-faq/
> *   http://www.ats.ucla.edu/stat/stata/
*
*   For searches and help try:
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*   http://www.ats.ucla.edu/stat/stata/


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