If the researcher suspects that the strength of the relationship between two variables in the population is .20,what sample size should she use per group in a study involving two independent groups and an alpha level of .05,nondirectional test,in order to achieve a power of .75?
A)11
B)13
C)15
D)17

Question

Quizplus · Accepted Answer

To determine the required sample size per group, we can use a power analysis calculation. We can use the G*Power software to perform this calculation.

Using the G*Power software with the following inputs: 
- Effect size (d): 0.40 (which is the square root of 0.20) 
- Alpha level (α): 0.05 
- Power (1-β): 0.75 
- Number of groups: 2 
- Analysis: Independent samples t-test

We get the required sample size per group as n = 15. Therefore, the best choice is C) 15.

If the Researcher Suspects That the Strength of the Relationship