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# Re: st: Calculating predicted probabilities at a given value of one of the independent variables

 From Richard Williams To statalist@hsphsun2.harvard.edu Subject Re: st: Calculating predicted probabilities at a given value of one of the independent variables Date Thu, 27 Oct 2011 00:59:55 -0500

```At 10:05 PM 10/26/2011, Vitorino, Maria Ana wrote:
```
Thanks!! But the results should be the same as in your previous suggestion, right? Or am I missing something?
```
```
Also, -help predict- talks about in-sample and out-of-sample predictions. An interesting example it gives shows how you could run the estimation on one sample and then compute the predictions using a totally different sample.
```
```
```Ana

```
On Oct 26, 2011, at 10:53 PM, "Richard Williams" <richardwilliams.ndu@gmail.com> wrote:
```
> At 06:06 PM 10/26/2011, Maria Ana Vitorino wrote:
>> Dear Statalist users,
>>
>> I would like to calculate some predicted probabilities after fitting a
>> multinomial logit model (asclogit). But, the twist is that I would
>> like to calculate these fitted values for a given level of one of the
>> independent variables. Namely, I would like to set one of the Xs to
>> zero when computing the predicted probability (but not in the
>> estimation).
>> do it in 2 steps? In the first step use  "predict xb" and in the
>> second step remove the component of xb that I'm not interested and
>> calculate the probability using "gen" and the logit formula?
>> Or is there a better way?
>
```
> I am going to slightly tweak my earlier advice. Assuming you only want in-sample predictions,
```>
> webuse sysdsn1, clear
> clonevar xmale = male
> mlogit insure age i.xmale nonwhite i.site
> predict p1 p2 p3 if e(sample)
> replace xmale = 0 if !missing(xmale)
> predict pp1 pp2 pp3 if e(sample)
>
>
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
> OFFICE: (574)631-6668, (574)631-6463
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> EMAIL:  Richard.A.Williams.5@ND.Edu
> WWW:    http://www.nd.edu/~rwilliam
>
> *
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*
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```
```
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME:   (574)289-5227
EMAIL:  Richard.A.Williams.5@ND.Edu
WWW:    http://www.nd.edu/~rwilliam

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```