Posted by Melissa Williams on .
A researcher is testing the hypothesis that consuming a sports drink during exercise improves endurance. A sample of n=50 male college students is obtained and each student is given a series of three endurance tasks and asked to consume 4 ounces of the drink during each break between tasks. The overall endurance score for this sample is M=53. For the general population, without any sports drink, the scores for this task average m=50 with a standard deviation of σ=12.
a. Can the researcher conclude that endurance scores with the sports drink are significantly higher than scores without the drink? Use a one- tailed test with α=.05.
b. Can the researcher conclude that endurance scores with the sports drink are significantly different than scores without the drink? Use a two- tailed test with α=.05.
c. You should find that the two tests lead to different conclusions. Explain why.
Briefly explain how increasing sample size influences each of the following. Assume that all other factors are held constant.
a. The size of the z- score in a hypothesis test.
b. The size of Cohen’s d.
c. The power of a hypothesis test.