Exercise 25: Conducting Power Analysis
Questions to Be Graded
1. 1. What is one approach a researcher can take when there is a lack of information in the
literature concerning effect sizes that can be used as a basis for her power analysis?
If the literature review does not produce any helpful effect size information, then the researcher
may consider contacting other investigators in the field to obtain guidance (Hulley, Cummings,
Browner, Grady, & Newman, 2013).
1. 2. Perform a power analysis based on a small hypothesized Cohen’s d, α = 0.05, and power
= 0.80, two-tailed, with two groups of equal size using G*Power. What is the required N?
The required N= 788 (Total Sample Size)
1. 3. Redo your power analysis from Question 2 using a power of 85% instead of 80%.
Questions to Be Graded
1. 1. What is one approach a researcher can take when there is a lack of information in the
literature concerning effect sizes that can be used as a basis for her power analysis?
If the literature review does not produce any helpful effect size information, then the researcher
may consider contacting other investigators in the field to obtain guidance (Hulley, Cummings,
Browner, Grady, & Newman, 2013).
1. 2. Perform a power analysis based on a small hypothesized Cohen’s d, α = 0.05, and power
= 0.80, two-tailed, with two groups of equal size using G*Power. What is the required N?
The required N= 788 (Total Sample Size)
1. 3. Redo your power analysis from Question 2 using a power of 85% instead of 80%.
