To test the effectiveness of a treatment, a sample of n=25 people is selected from a normal population with a mean of 60. After the treatment is administered to the individuals in the sample, the sample mean is found to be M=55
a. Compute Cohen's d to measure effect size for both test ( standard deviation 20 and 10)
b. If the population standard deviation is 10, can you conclude that the treatment has a significant effect? Use a two-tailed test with .05
c. If the population standard deviation is 20, can you conclude that the treatment has a significant effect? Use a two-tailed test with .05.
d. Briefly describe how the standard deviation influences the outcome of the hypothesis test. How does standard deviation influence measures of effect size?