Module 9 Worksheet: Comparing Groups and Effect Sizes
Scenario
Two groups differ, the difference is statistically detectable, and a decision is about to be made on the strength of it.
Data
Dataset: group-comparison-summary.csv
| group_name | sample_size | mean_score | standard_deviation | notes |
|---|---|---|---|---|
| No practice quiz | 48 | 68 | 12 | baseline group |
| One practice quiz | 52 | 72 | 11 | small improvement |
| Three practice quizzes | 50 | 79 | 10 | stronger improvement |
| Optional review session | 28 | 81 | 14 | self-selected group |
| Required review session | 55 | 76 | 9 | assigned group |
Your Task
Write a cautious group-comparison paragraph using mean, sample size, spread, and one limitation.
Questions
- How large is the difference, in the units of the measure?
- Is it distinguishable from zero?
- Is it large enough to act on? Say what that depends on.
- What sample size produced this result?
- What figure should have been agreed before the analysis?
- What does the interval say about the plausible range?
- What is your recommendation?
Write Your Conclusion
Give the difference, its interval, and your recommendation — including the case for doing nothing.
Self-Check
- Did I report the difference in real units?
- Did I separate statistical from practical significance?
- Did I name the threshold that should have been set first?
- Did I consider doing nothing?