Averaging probabilities?

Hi all.

<b>Background:</b> I'm working on a study looking at neonatal
hypoglycemia as a binary outcome, using infants who have neonatal
hypoglycemia (cases) matched for comparison with infants who don't
(controls). I've run a univariate model using conditional logistic
regression in Stata 9, and for each observation, have predicted the
conditional probability of developing neonatal hypoglycemia given
gestational age. The probability value output by Stata is called

P(Neonatal Hypoglycemia | Single outcome w/in group)

and I want to plot this against gestational age to show that there is
a steep negative slope up to a certain gestational age, after which
point it levels out. (Translation: risk of hypoglycemia decreases as
gestational age increases, to a point, then becomes stable.) I'd like
to do this cleanly, with one summary probability, like an average,
[that is, one y-value] for each gestational age (x-value), rather than
the 30 or so I have for each category now.

<b>Question:</b> Can I average the probabilities for each observation
within a specified gestational age (to get that one y-value for each
age group)? I seem to remember that taking the average of a
probability is Bad Math but I can't find anything to verify it, so I
may not be remembering correctly.
.

Relevant Pages

  • Re: Averaging probabilities?
    ... hypoglycemia matched for comparison with infants who don't ... conditional probability of developing neonatal hypoglycemia given ... gestational age. ... but now you want to use age categories in the plot? ...
    (sci.stat.math)
  • Re: Averaging probabilities?
    ... hypoglycemia matched for comparison with infants who don't ... The probability value output by Stata is called ... and I want to plot this against gestational age to show that there is ...
    (sci.stat.math)