What is a potential problem with evaluating program effectiveness solely on crash reductions?

• A. They prove causation
• B. They ignore other factors
• C. They could be due to other factors
• D. They require no data

Answer: (C)

When evaluating program effectiveness, relying only on crash reductions tests whether the program alone caused the change. A key issue is that crash counts can drop for reasons unrelated to the program. Crash outcomes are influenced by many factors—changes in traffic volume, weather, daylight, road improvements, enforcement in other areas, or broader safety trends. If crashes go down after a program is implemented, it might reflect these other factors rather than the program itself. To build a convincing case, you’d want analyses that control for these confounders or use additional indicators (like exposure data, longer time trends, or a comparable control area) so you can separate the program’s effect from other influences.