A major oil company would like to improve its tarnished image following a large oil spill. Its marketing department develops a short television commercial and tests it on a sample of n = 15 participants. People's attitudes about the company are measured with a short questionnaire both before and after viewing the commercial. You have been asked to analyze the data and find out if the commercial worked or not.

What statistical test will you use?

Regression

Correlation

One-way ANOVA

Repeated measures t-test

Independent samples t-test

One-sample t-test

z-test

Then, answer why you picked the test you did?