Question

Which of the following is appropriate for a related-samples t test?

A researcher wants to compare the level of honesty (based on an honesty scale) in politicians to the level of honesty in students

A researcher wants to compare the scores on a optimism measure between two universities

A researcher wants to examine the association between liking for energy drinks and tendency to be a “morning person” among a group of students

A researcher wants to compare the level of sat scores at the beginning of a preparation class to their sat scores at the end of the class.

Answer 1

(A) it is incorrect because the sample of politicians and sample of students are independent and we never use related samples t test for independent samples

(B) it is incorrect because it is given that we have samples from two universities, i.e. two independent samples. So, it is not appropriate for related samples t test

(C) it is incorrect because related sample t test is used for comparison of means, but not the for association. So, this example is inappropriate

(D) It is correct because we have same set of students or same sample data of students whose sat scores are compared at beginning and end of the class

So, this is a dependent samples case and we can use related samples t test.