You wonder if using the online practice questions help or not. You think they will improve grades but others say they are confusing and hurt their grade. To test it you examine the scores on the Percentile Rank and Percentile Point Questions from test 1. These questions had a maximum score of 20. You find that the 100 people who used the chapter 3 online practice question feature and their average score on that question was 14.9 (St dev = 4.5). Historically, over the past several years the typical score on these questions is 12.1 (St Dev = 4.8).

a) What would you conclude?

b) Are you absolutely certain that use of the online questions are the cause for the difference?

What would you have to do in order to be more certain the online practice questions truly do help?

(hint: is this a study or an experiment?)