Applying ttests

Instructions: Complete the problems below. For each, walk through and report the 6 steps of hypothesis testing. Be sure to directly report which test you have selected, and to share appropriate statistical values (i.e., any value necessary for your analysis). Hint: It may help to follow your worksheet examples.

1. On its Web site, the Princeton Review claims that students who have taken its Graduate Record Examination (GRE) Prep course improve their scores, on average, by 210 points. (No other information is provided about this statistic.) Treating this average gain as a population mean, a researcher wonders whether the far cheaper technique of practicing for the GRE on one's own would lead to a different average gain. She randomly selects five students from the pool of students at her university who plan to take the GRE. The students take a practice test before and after 2 months of self-study. They reported gains of 160, 240, 340, 70, and 250 points.

1. Did the scores of students who practiced on their own significantly differ from those who take the GRE prep course? (Share your work for all 6 steps of the hypothesis test.)

Provide Confidence Intervals and Effect size estimates for your test and report your results