From Mobility for the Poor: Car-Sharing, Car Loans, and the Limits of Public Transit by Jeff Khau.  An example of the importance of establishing the difference between correlation and causation; of the importance of directionality of causation; of context; of root cause analysis; and goal definition.

Theoretically, one can look at this graph and legitimately make the argument that in order to increase public utilization of public transportation, one ought to increase the average commute time.  It is a good exercise in critical thinking to spot the fallacy of such an interpretation.

Tags: Causation, Conflicting Goals, Context, Correlation, Definitions, Directionality, Goal Definition, Root cause, Trade-Offs