STAT 301 Lecture Notes - Confidence Interval, Sampling Distribution, Point Estimation
Document Summary
We want to make inferences about 1 2, where 1 and 2 come from different populations. So p1 p2 is the point estimate for 1- 2. When we perform a hypothesis test, we assume h0 is true. When 1 = 2, we can combine the two populations into one where the true proportion is. So we can combine our samples into one sample of size n1 + n2, from which we get an estimate of the overall population proportion ( ), denoted pc or p . That is, pc is the sample proportion from the combined sample of size n1 + n2 pc = p = n1 p1+n2 p2 n1+n2. Since we assume 1 = 2 = , we can assume p1 p2 pc (theoretically, p1 would = p2, but won"t be in every case. We use pc as an estimate for both) If sampling distribution assumptions hold, then ( p1 p2) ( 10 20) pc(1 pc) n2.
