Should you have a cup of coffee to make you more alert when studying for a big test? A researcher is interested in studying the effect of caffeine, and he comes up with the following plan for an experiment. The experiment will involve 100 volunteers each of which will take a memory test 20 minutes after drinking cola. Some volunteers will be randomly assigned to drink caffeine-free cola; some to drink regular cola (with caffeine), and the others a mixture of the two (getting a half dose of caffeine). For each volunteer, a test score (the number of items recalled correctly) will be recorded. The volunteers will not be told which type of cola they have been given, but the researcher who evaluates the results will prepare the cups of cola right on the spot (out of sight of the volunteers).

(a) What type of design is this experiment? ? a glass of cola a volunteer blocking variable response variable confounding variable caffeine caffeine-free cola and regular cola no caffeine, half dose of caffeine and full dose of caffeine completely randomized design randomized block design

(b) The treatments are ? a glass of cola a volunteer blocking variable response variable confounding variable caffeine caffeine-free cola and regular cola no caffeine, half dose of caffeine and full dose of caffeine completely randomized design randomized block design

(c) The score of the memory test is the ? ? a glass of cola a volunteer blocking variable response variable confounding variable caffeine caffeine-free cola and regular cola no caffeine, half dose of caffeine and full dose of caffeine completely randomized design randomized block design

(d) The study finds that the group of students who drink regular cola has a significantly higher average test score than the group who drink caffeine-free cola. This implies:
A. The difference in the average test score between the regular cola group and the caffeine-free cola group is so large that it can be explained by chance.
B. The difference in the average test score between the regular cola group and the caffeine-free cola group is so small that it can be explained by chance.
C. The difference in the average test score between the regular cola group and the caffeine-free cola group is so small that it cannot be explained by chance.
D. The difference in the average test score between the regular cola group and the caffeine-free cola group is so large that it cannot be explained by chance.