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Topic: hypothesis test question on two proportions
Replies: 0

 prof Posts: 5 Registered: 7/10/06
hypothesis test question on two proportions
Posted: Jul 10, 2006 5:29 PM

In the two population proportion test of H0: p1 = p2 vs Ha: p1 not
equal p2 with a los of 0.05, one way to conduct the test is to
construct a 95% CI on p1 - p2. Then, if the interval contains "0",
accept H0; otherwise reject H0. An alternate way is to calculate the z
statistic under the assumption that H0 is true and compare to the 5%
critical region. If the statistic is in the critical region, reject H0;
otherwise accept H0. The question is: do the two methods give identical
conclusions? The answer is not obvious to me since in the CI approach
an assumption of H0 being true is not used; thus there are separate
estimates for the two sample proportions which appear in the CI
formula. whereas, in the test statistic approach, H0 being true is
assumed; thus giving a combined estimate for the common proportion p
which is used in the test statistic.. It is not obvious that identical
conclusions would always be reached. Help please!!!