Question

Donna is testing to see if going to the beach to study for a test affects test score. Her data consists of 200 people who went to the beach and 250 people who didn’t go to the beach.

What test should she use to analyze her data? Don’t assume that any information about the population exists unless it is stated. Furthermore, it may be that in some cases a t-distribution and a z-distribution are very similar. This does not mean that there are two acceptable answers. Pick the best answer. Note: You do not have to distinguish between independent samples with and without homogeneity of variance.

answers are the following:

A)a repeated (related) measures t-test

B)a one-sample t-test for means

C)a one-sample z test for means

D)a one sample z-test for proportions

E)an independent samples t-test

F)none of these tests

Answer 1

Answer is

E) an independent samples t test

Note : In this example , we have two samples : Sample 1 : went to the beach , Sample 2 : Did not go to the beach .

Thus , we have two unrelated /independent samples .

We have to compare the mean score between the two groups based on the sample observations .

Let be the population mean score of first group ( go to beach) and be the population mean score of second group ( do not go to beach)

We have to test whether and differ based on sample observations .

Thus , it is a two sample t test , also known as independent sample t test for mean

In repeated measure ( related) t test there are two sets of observations but they are based on same subject( same set of students) at two situations or time points . Thus it is not a repeated measure t test .