Chapter 10, Problem T10.10SPT

To determine

To find out the power of the test if the researches want to be able to detect a five-point difference instead.

Answer to Problem T10.10SPT

Option (a) is the correct option.

Explanation of Solution

It is given in the question that if a researcher wants to be able to detect a seven-point difference then a power of $80\%$ is to be needed. Then for a researches want to be able to detect a five-point difference instead, we know that a larger difference are easier to detect and thus have a higher power.

Therefore, the difference is decreased from $7\text{ to }5$ , then the power will also decrease and thus the correct answer is (a) i.e. the power of test would be less than $80\%$ .