7.126 Ego strengths of MBA graduates: power.

In Exercise 7.93 (page 410), you found the power for a study designed to compare the “ego strengths’’ of two groups of MBA students. Now you must design a study to compare MBA graduates who reached partner in a large consulting firm with those who joined the firm but failed to become partners.

Assume the same value of and use . You are planning to have 20 subjects in each group. Calculate the power of the pooled two-sample test that compares the mean ego strengths of these two groups of MBA graduates for several values of the true difference. Include values that have a very small chance of being detected and some that are virtually certain to be seen in your sample. Plot the power versus the true difference and write a short summary of what you have found.