A psychopharmacologist (a psycholgist interested in the effects of drugs and phy

Question

A psychopharmacologist (a psycholgist interested in the effects of drugs and physiology) is interested in determining the effects of caffeine (from coffee) on test performance. Twenty students from a large introductory psychology class volunteered to participate in the study; all were dedicated coffee drinkers and all drank caffeinated coffee. The volunteers were then randomly divided into two groups such that there were ten students in each group. One group of 10 students was asked to study the test material while drinking their normal doses of coffee, and to take the test while drinking their normal doses of coffee before the test. This group is called the “Coffee with Test” group.

The second group of 10 students was asked to study the test material while drinking their normal doses of coffee, but to take the test without having consumed coffee for at the least 3 hours beforehand. This group is called the “No-Coffee with Test” group. One student from the “No-Coffee with Test” group became ill and was unable to sit for the test. The researcher recorded the number of correct responses on the test. One could get up to 15 items correct on the test. The scores are below.

Which hypothesis test needs to be employed here?

Coffee with Test
(Number Correct)
Group 1 No-Coffee with Test (Number Correct)
Group 2 8 7 10 12 14 9 12 9 9 5 9 6 13 14 8 6 12 7 11

Explanation / Answer

Answer: Option D. Independent t test.

The independent-samples t-test compares the means between two unrelated groups on the same continuous, dependent variable.

Here since the sample size is not large enough and there are 2 independent groups of data, the independent t test is to be used.

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