Dr. Suess wants to know if people are happier after watching a silly (comedy) movie than if they watched a more serious film such as a documentary. To answer this question he recruited 20 college students to watch a movie and then fill out some personality scales that measure happiness (among other things). He had 10 of the students watch the comedy and the other ten watched the documentary. What statistical test would be required to answer this question?
The correct answer and explanation is :
The appropriate statistical test for this study is the independent samples t-test (also known as an unpaired t-test).
Explanation:
The independent samples t-test is used when comparing the means of two independent groups to determine whether there is a significant difference between them. In this case, the study involves two separate groups of college students—one group that watched a comedy movie and another that watched a documentary. The goal is to determine if the happiness levels (as measured by personality scales) differ significantly between the two groups.
Here’s why the independent samples t-test is the best choice:
- Two Independent Groups:
- The study involves two distinct groups (comedy watchers vs. documentary watchers).
- Each student is assigned to only one condition (not watching both movies).
- Dependent Variable:
- The dependent variable (happiness score) is measured on a continuous scale (likely an interval or ratio scale).
- The t-test compares the mean happiness scores of the two groups.
- Comparing Means:
- The test determines if the mean happiness score of one group (comedy viewers) is significantly different from the mean of the other group (documentary viewers).
Steps in Conducting the Independent Samples t-Test:
- State the Hypotheses:
- Null Hypothesis (H₀): There is no significant difference in happiness scores between comedy and documentary viewers.
- Alternative Hypothesis (H₁): There is a significant difference in happiness scores between comedy and documentary viewers.
- Check Assumptions:
- Normality: The happiness scores should be normally distributed within each group.
- Homogeneity of Variance: The variance in happiness scores should be roughly equal between groups.
- Run the Test:
- Calculate the t-statistic and p-value to determine statistical significance.
- Interpret the Results:
- If p < 0.05, reject H₀ and conclude that the type of movie significantly affects happiness.
This test effectively answers Dr. Seuss’s research question by determining if comedy movies make people happier than documentaries.