Suppose that the laboratory referred to in Exercise 8.7 decided not to run one group and compare it against , but instead to run two groups (one with and one without lesions). They still expect the...

Suppose that the laboratory referred to in Exercise 8.7 decided not to run one group and compare it against , but instead to run two groups (one with and one without lesions). They still expect the same degree of difference.

a. How many subjects do they need (overall) if they are to have power 5 .60?

b. How many subjects do they need (overall) if they are to have power 5 .90?

A research assistant ran the experiment described in Exercise 8.8 without first carrying out any power calculations. He tried to run 20 subjects in each group, but he accidentally tipped over a rack of cages and had to void 5 subjects in the experimental group. What is the power of this experiment?