Expert Answers

1) For each of the following studies, say whether you would use a t test for dependent means or a t test for independent means.

a) A researcher randomly assigns a group of 25 unemployed workers to receive a new job skills program and 24 other workers to received the standard  job skills program, and then measures how well they all do on a job-skills test.

b) A researcher measures self-esteem in 21 students before and after taking a difficult exam

c) A researcher tests reaction time of each of a group of 14 individuals twice, once while in a very hot room and once while in a normal-temperature room.

2) A developmental psychologist compares 4-year olds and 8-year olds on their ability to understand the analogies used in stories.  The scores for the five 4-yr olds were 7, 6, 2, 3, and 8. The scores for the three 8-yr olds were 9, 2, and 5. Using an alpha level of 0.05,  do older children do better?

a) Use the 5 steps of hypothesis testing

b) sketch the distributions involved

c) explain your conclusions