Free practice · numeric · medium
Practice
Calculate a comparison change
A pilot group's average wait fell from 20 to 14 minutes. By how many minutes did it fall?
Causal evidence ladder
Timing is necessary, but alternatives still need testing
- ObserveDescribe the outcome
- SequenceCause must come first
- MechanismExplain the pathway
- CompareUse equivalent cases
- AlternativesMeasure other changes
- BoundUse evidence-sized language
A causal interpretation grows stronger when sequence, mechanism, fair comparison, repeated evidence, and competing explanations agree.