Study guide: From Change to a Causal Question
Audit definitions, compare cases, and write cause conclusions that acknowledge alternatives.
Ideas to explain in your own words
- Identify alternative explanations before attributing a change to one event.
- Determine whether before-and-after figures use the same definition.
- Calculate changes across two cases and state a conditional interpretation.
- Explain how new evidence would strengthen, weaken, or leave a cause claim unresolved.
Watch your reasoning
- The records show an increase alongside several changes. They establish neither the bus’s exact effect nor that its effect was zero. Additional comparisons could help distinguish explanations.
- One count permits repeats and the other does not. The difference is computable as numbers but does not establish change in one consistent quantity.
- Differences can be computed with unequal starting totals. Causal interpretation still requires comparability beyond the supplied arithmetic, and entries are not unique passengers.
- Causation asks about the counterfactual outcome. The link records coupon use, not the unobserved absence-of-sign behavior.
A worked review example
Test a historical cause claim: Visits rose by 260 − 200 = 60 per month. The timing makes the bus a possible contributor, but added stalls and population growth are alternatives. The records do not isolate how much each factor contributed. Audit a Change in Measurement: “260−200=60 is a difference between entry and unique-person figures, not established visitor growth. For 1953, counting unique people alongside entries could show the repeat-entry gap; comparable unique-person totals in both periods would support a growth comparison, though not isolate a bus cause.” Use a Comparison Without Calling It an Experiment: “Alder rose 60 entries, Birch 30, so Alder’s increase exceeded Birch’s by 30. That is not an isolated bus effect: Alder also added ten stalls, and comparable underlying trends are not established. The comparison is informative but limited.” Write a Conditional Cause Conclusion: “Entries rose by 40. The sign is a plausible contributor, and twenty entry occasions carried sign-linked coupons, but the craft event also began and coupon users might have attended anyway. A similar increase during event-only periods would weaken sign-only attribution; stable event-only periods followed by repeated sign-associated increases could strengthen it, subject to comparable conditions.”
Make a practice plan
- Try the supplied lesson problems without looking at the answers.
- Compare your method with the worked examples and explain any correction.
- Use the new review cases, then complete the transfer task on paper or in your own document.