Hypothesis testing using paired-samples t-test

3. A total of 6 people take a cognitive test before and after consuming alcohol. Below are their scores. Assuming that scores are predicted to decrease following alcohol consumption, conduct a paired-samples t-test and compare it to the critical t-value to determine if the difference is significant. Assume a one-tailed hypothesis with = .05. Based on these results what can we infer about the effect that alcohol had on peoples' scores on the test? (3 marks)

Before After

Person 1 20 14

Person 2 26 23

Person 3 20 22

Person 4 18 13

Person 5 27 20

Person 6 26 21

Calculate the effect size (i.e., Cohen's d) and indicate the relative size of the effect. (1 mark)