Statistics Homework

Factors Affecting Power in the t Test

After completing this unit's assigned readings, discuss one of the following questions:

1. A researcher can do several things to try to increase the  magnitude of the effect size d. What are these? Suppose that you can  increase the effect size d while holding group sizes n 1 and n 2  constant. How will an increase in effect size d influence the magnitude  of t?
2. Several factors influence statistical power for a one-sample t test. How does statistical power change (increase or decrease) for each of the following changes?      
   • When d (effect size) increases.
   • When N (sample size) increases.
   • When the alpha level is made smaller.

Explain your answer. For example, if we know ahead of time that the  effect size d is very small, what does this tell us about the N we will  need in order to have adequate statistical power? (We assume that all  other terms included in the r ratio remain the same.)