An urban planner examines police-report data for many cities and towns and discovers that cities with professional football teams tend to have higher numbers of reported small crimes, such as burglary.

The association does not show that football teams cause crime. Cities with professional football teams are often larger, and larger cities have more people and therefore may have more reported small crimes overall. City size is a plausible factor that helps explain the higher crime counts, so the best choice is that cities with football teams tend to be large.

AI-written and checked against the verified answer.