Which weather condition is associated with the highest percentage of crashes in the data?

Which weather condition is associated with the highest percentage of crashes in the data?

• A. Icy roads
• B. Rain
• C. Fair weather conditions
• D. Snow

Answer: (C)

The main idea here is that the distribution of crashes by weather condition is driven by exposure—how much driving occurs in each condition. When weather is fair, people drive more overall, so the total number of crashes in those conditions tends to be larger. Even though driving is riskier per mile in icy, rainy, or snowy weather, there are fewer miles driven in those conditions, which lowers their share of all crashes. So, the data show the largest percentage of crashes happening under fair weather conditions, not because it’s the most dangerous, but because it involves the most driving activity.

The main idea here is that the distribution of crashes by weather condition is driven by exposure—how much driving occurs in each condition. When weather is fair, people drive more overall, so the total number of crashes in those conditions tends to be larger. Even though driving is riskier per mile in icy, rainy, or snowy weather, there are fewer miles driven in those conditions, which lowers their share of all crashes. So, the data show the largest percentage of crashes happening under fair weather conditions, not because it’s the most dangerous, but because it involves the most driving activity.