st: predict after clogit

[Jeph Herrin <junk@spandrel.net>]

I am surprised by the results I am getting from
-predict- after -clogit- and wonder if I am missing
something.


. clogit endpoint age female, strata(site)
[output suppressed]
. predict prob1
(option pc1 assumed; conditional probability for single outcome within 
group)
. sum prob endpoint

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
       prob1 |       630    .0365079    .0776009   .0053902          1
    endpoint |       630    .4539683    .4982722          0          1


Why is the predicted so far off from the actual? Compare with the logit
model:

. logit endpoint age female
[output omitted]
. predict prob2
(option pr assumed; Pr(endpoint))
. sum prob2 endpoint

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
       prob2 |       630    .4539683    .0251972   .4150936   .4819036
    endpoint |       630    .4539683    .4982722          0          1


Am I using -predict- incorrectly after -clogit-? Is it a coincidence
that -invlogit(prob1)- *does* look like the actual.

. gen invlogpr1=invlogit(prob1)
. sum invlogpr1

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
   invlogpr1 |       630    .5090418     .018543   .5013475   .7310586


Thanks for any insights.

Jeph




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