Question

# A psychologist is interested in investigating whether people who never owned a pet are happier after...

1. 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. (11 points)
 Before Pet After Pet 10 15 9 9 11 10 11 5 9 19 17 15
1. 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. (3 points)
1. 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? (2 point)
1. Calculate the estimated Cohen’s d to measure the effect size for this study. (1 point)
1. Interpret your results as if you were reporting them for a journal article. Use APA style. (5 points)

(a)

 Before Pet After Pet Difference 10 15 -5 9 9 0 11 10 1 11 19 -8 5 17 -12 9 15 -6 Mean -5 Standard 4.89897949 n 6 t -2.5

The test statistic is -2.5.

(b) The p-value is 0.055.

Since the p-value (0.055) is greater than the significance level (0.05), we cannot reject the null hypothesis.

(c) Cohen's d =5/4.89897949 = 1.02

(d) Since the p-value (0.055) is greater than the significance level (0.05), we cannot reject the null hypothesis.

Therefore, we cannot conclude that people who never owned a pet are happier after getting a pet.

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