Causal Claim Reviewer — illustrative example

INPUT
Signups increased after a homepage edit while an advertising campaign also launched.

RESULT
Treat the increase as an observation; both changes and other factors may contribute, so the edit's causal effect remains unresolved.

REVIEW
A causal claim requires more than two things changing together. Identify alternative explanations and what the design can actually establish.

This is a teaching example, not a live execution record.