If speed feedback signs correlate with a reduction in speeding-related fatalities the following year, without further information, this is an example of which statistical concept?

• A. Correlation
• B. Causation
• C. Case-control
• D. Cohort study

Answer: (A)

This is about correlation versus causation. Observing that speed feedback signs are linked with fewer speeding-related fatalities in the following year shows a relationship between two variables. That relationship is correlation: the two outcomes move together in some pattern. However, correlation doesn’t prove that the signs caused the reduction. Other factors—like changes in enforcement, other safety programs, weather, traffic volumes, or random variation—could explain the drop. To claim causation, you’d need stronger evidence that rules out these alternative explanations, such as a study design that controls for confounders or demonstrates that implementing the signs leads to lower fatalities. Case-control and cohort describe specific study designs and could show associations, but the scenario as stated doesn’t establish those designs. So the concept illustrated here is correlation.