predxcat and predxcon use the strandard error of the prediction. I plan
to update these programs to take advantage of the Stata 8.0 graphics as
soon as possible (in otherwords, when I figure out how to do it), and
will post them for anyone who is interested.
Joanne Garrett
"Daniel, Gregory" wrote:
>
> I have just tried using the predxcat command, but I noticed that the
> confidence intervals seem too narrow and are pretty much the same as the
> CI's obtained when using:
>
> Adjust x2 x3 x4, by(x1) pr ci
>
> These CI's are calculated using the standard error from the predicted index,
> not the predicted probability---correct?
>
>
> Christer wrote:
>
> Check out
> Predxcon or predxcat
> or
> logpred , regpred
> or
>
> The commands at Scott Long's Homepage (http://www.indiana.edu/~jslsoc/)
>
> Greg wrote:
>
> To predict probabilities and 95% CIs of the predicted probabilities after a
> multivariate logistic model, I have previously used the following predict
> command:
>
> logistic y x1 x2 x3
> predict lr_index, index
> predict se_index, stdp
>
> gen p_hat = exp(lr_index)/(1 +exp(lr_index))
> gen lb = lr_index - invnorm(0.975)*se_index
> gen ub = lr_index + invnorm(0.975)*se_index
> gen plb = exp(lb)/(1+exp(lb))
> gen pub = exp(ub)/(1+exp(ub))
> bysort x1: tabstat p_hat plb pub
>
> However, this code does not allow me to predict probabilities,
> by(x1), while keeping the other covariates held constant, as the adjust
> command does.
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
