In: Statistics and Probability
A psychologist is interested in investigating whether people who never owned a pet are happier after getting a pet. A questionnaire about their level of happiness is administered to a group of 20 to 29 year-olds when they before they get a pet and after they get a pet. The data are below.
Before Pet |
After Pet |
|
10 |
15 |
|
9 |
9 |
|
11 |
10 |
|
11 5 9 |
19 17 15 |
Calculate a t-statistic to compare the happiness levels before and after getting a pet. The variance for the difference scores is sD2 = 24. Show your work.
Assume that the psychologist uses an =.05, two-tailed, df = (6-1) = 5. The tcritical value = +2.57 and the p-value associated with their t-test statistic was p = .055. Should the psychologist reject or fail to reject the null hypothesis, and why?
Calculate the estimated Cohen’s d to measure the effect size for this study.
Interpret your results as if you were reporting them for a journal article. Use APA style.