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st: Confidence Interval for Proportion

From   "Martin Weiss" <>
To   <>
Subject   st: Confidence Interval for Proportion
Date   Tue, 11 Mar 2008 14:24:42 +0100

Dear Statalisters,

try this in Stata:

sysuse auto, clear
proportion rep78
matrix define A=e(b)
matrix define B=e(V)
count if rep78!=.
*Upper/Lower Bound for proportion of "1"
di A[1,1]+invnormal(1-0.05/2)*sqrt(A[1,1]*(1-A[1,1])/`r(N)')
di A[1,1]-invnormal(1-0.05/2)*sqrt(A[1,1]*(1-A[1,1])/`r(N)')
*Standard Error for "1"
*Mistake obviously there...
di sqrt(A[1,1]*(1-A[1,1])/`r(N)')

Then let me know: why do I not hit the correct CI for the proportion of "1"
in the repair record? Something`s wrong with the standard error, I do not
know what, though...

Martin Weiss

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