Sayer, Bryan
> Gee, personally I would suggest just doing them in the
> spreadsheet, if that
> is the way the data came. (Standard error of proportion =
> sqrt[p*(1-p) / n]
> , 95% c.i. = p +/- 1.96*se(p))
That is a common textbook formula, but it
behaves much worse than is widely realised,
even if p is not close to 0 or 1 and n
is moderately large.
Much recent literature (some 2001 or 2002) shows how lousy
it is, and how there are much better alternatives,
which do _not_ include the so-called "exact"
Clopper-Pearson interval implemented by -ci-
and -cii- for binomial proportions. ("Exact" is
a propaganda term here.)
Some alternatives are implemented by -cij-/-ciji-
and -ciw-/-ciwi- on SSC. The help files for
those packages -- which have just been updated --
contain much more detail and several references.
The approach suggested in my reply to Paul
can readily be extended to use either -ciji-
or -ciwi-.
(The latter has nothing to do with New Zealand.)
Nick
[email protected]
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