In a random sample of patient records in Cutter Memorial Hospital, six-month postoperative exams were given in 90 out of 200 prostatectomy patients, while in Paymor Hospital such exams were given in 110 out of 200 cases. In a left-tailed test for equality of proportions, the test statistic is:
A)-1.96
B)-2.00
C)-4.00
D)-3.48

Question

Quizplus · Accepted Answer

The test statistic for a difference in proportions is calculated using the formula for the z-test for two proportions. Here, we are comparing the proportion of six-month postoperative exams given in Cutter Memorial Hospital (p1) to the proportion in Paymor Hospital (p2). Given p1 = 90/200 = 0.45, p2 = 110/200 = 0.55, the sample sizes n1 = n2 = 200, and using the formula for the z-test statistic for two proportions, we find that the test statistic is approximately -2.00. This calculation involves finding the difference between the two proportions, calculating the standard error of the difference, and then dividing the difference by the standard error to get the z-score.

In a Random Sample of Patient Records in Cutter Memorial