In an introductory statistics class in which regular quizzes are given, should the first quiz be easy (to give students confidence) or hard (to convince students to work harder)? The response variable will be grades on a later exam that is common to all students.
(a) Describe an observational study to answer this question.
(b) Describe a confounding variable that is likely to impact the results of the observational study.
(c) Describe a randomized experiment designed to answer this question.