STAT 400 Lecture AL1 Spring 2015 Dalpiaz Answers for 7 3 8 3 Part 2 Consider two dichotomous populations with success proportions p 1 and p 2 respectively Consider the sample proportions p 1 where x1 n1 p 2 and x2 n2 n 1 and n 2 are the sample sizes and x 1 and x 2 are the numbers of successes in the two samples from populations 1 and 2 respectively If n 1 and n 2 are large then mean p 1 p 2 p 1 p 2 and standard deviation is approximately normal with p 1 1 p 1 p 2 1 p 2 n1 n2 The confidence interval for the difference between two population proportions p 1 p 2 is p 1 p 2 z 2 p 1 1 p 1 p 2 1 p 2 n1 n2 H1 p1 p2 H0 p1 p2 H1 p1 p2 H1 p1 p2 Test Statistic z p 1 p 2 p 1 p 1 n 1 n 1 2 where x x n p n p p 1 2 1 1 2 2 n1 n 2 n1 n 2 1 In a comparative study of two new drugs A and B 120 patients were treated with drug A and 150 patients with drug B and the following results were obtained a Drug A Drug B Cured Not cured 78 42 111 39 Total 120 150 Construct a 95 confidence interval for the difference in the cure rates of the two drugs 111 0 74 p B 78 0 65 p A 150 120 95 confidence level 0 74 0 65 1 96 0 09 0 11 b 0 05 2 0 025 z 1 960 2 0 74 1 0 74 0 65 1 0 65 150 120 0 02 0 20 We wish to test whether drug B has a higher cure rate than drug A Find the p value of the appropriate test Claim p A p B H 0 pA pB p vs x 1 x 2 78 111 189 0 70 n 1 n 2 120 150 270 H 1 pA pB 0 65 0 74 Test Statistic Z P value Left tailed 1 1 0 70 0 30 120 150 P value P Z 1 60 0 0548 1 60
View Full Document
Unlocking...