Does caffeine make you more alert? Should you drink a caffeinated drink before studying for a big exam? A study on the effect of caffeine involved asking 120 volunteers to take a memory test 20 minutes after drinking a prepared beverage. 40 volunteers were randomly assigned to drink a caffeine free soda/pop/cola, 40 other volunteers were given a caffeinated soda/pop/cola to drink and the remaining volunteers received a little bit of both mixed together (half the amount of caffeine). For each volunteer, a test score (the number of items recalled correctly) was recorded. The volunteers were not told which type of drink they were being given, but the researchers for the study prepared the drinks on the spot and conducted the experiment.

a) (2 pts) What type of study is this (be specific)?

b) (2 pts) What's the response variable?

c) (2 pts) What's the explanatory variable?

d) (2 pts) State the three principles of good experimental design and state if each was followed?

e) (2 pts) What might be a lurking variable in the study?

f) (2 pts) How might potential bias in this study be eliminated?

Answer all parts (a-f) of the question in the box. Label all parts of your answer.