[Rd] Confidence interval calculation in prop.test (PR#9325)
rmjohnston at mac.com
rmjohnston at mac.com
Tue Oct 31 02:50:09 CET 2006
Full_Name: Richard Johnston
Version: 2.4.0
OS: OS X
Submission from: (NULL) (69.169.0.241)
The confidence interval calculation for prop.test appears incorrect when
alternative="greater" . The upper limit is always set to 1.0000. The lower
limit appears to be correct.
> total=c(250,250)
> success=c(55,31)
> prop.test(success,total,alternative="greater",correct=TRUE)
2-sample test for equality of proportions with continuity correction
data: success out of total
X-squared = 7.4289, df = 1, p-value = 0.003209
alternative hypothesis: greater
95 percent confidence interval:
0.03693065 1.00000000
sample estimates:
prop 1 prop 2
0.220 0.124
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