Question

Which of the following is INCORRECT?

A) Surveys have been widely used by politicians around the wold as a way of monitoring the opinions of the electorate. Six months ago, a survey was undertaken to determine the degree of support for a national party leader. Of a sample of 1,100, 56% indicated that they would vote for this politician. This month, another survey of 800 voters revealed that 46% now support the leader. Can we infer that the national leader's popularity has decreased? The test the researcher should use would be two population proportions

B) A statistics professor wanted to test whether the grades on statistics tests were the same for upper and lower classmen. The professor took a random sample of size 12 from each and conducted a test determining that the grades were equal. For this situation, the professor should use a matched pairs t-test

C) A Marine drill instructor recorded the time in which each of 10 recruits completed an obstacle course both before and after basic training. To test whether any improvement occurred, the instructor would use a t-distribution after 9 degrees of freedom

D) A researcher is curious about the effect of sleep on students' test performances. He chooses 50 students and gives each two tests: one given after four hours of sleep and one after eight hours of sleep. The test the researcher should use would be matched pairs t-test

Answer 1

Option B) is incoreect.

Because, professor want to test score for both lower classmen and upper classmen. Here both sample are not dependent / related to each other so professor should use independent two sample t test. Paired t test is not appropriate hence option b is incorrect.