[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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