Question 1

Do vehicle brands with higher crash frequency also exhibit higher severe crash rates, or are crash frequency and severity largely independent?

Analysis

Visualizations 1–3 suggest that crash frequency and crash severity are not strongly tied together for the six selected brands.

The first chart shows that the selected brands sit in the middle range of total crash counts compared with the broader top-20 brands. Within the selected group, Lexus and Acura are among the higher-volume brands, while GMC has the lowest crash count and BMW is also not among the highest-volume brands.

The second chart shows that BMW has the highest severe crash rate at about 1.10%, clearly above the other five brands. GMC is next at around 0.77%, while Acura, Jeep, Lexus, and Mazda cluster more tightly between roughly 0.65% and 0.74%.

The third chart confirms this mismatch between frequency and severity. BMW stands out as high severity without having the highest crash count, while Acura and Lexus have relatively high crash counts but lower severe crash rates. That pattern supports the idea that more crashes do not automatically mean more severe crashes.

Key Insights

• Crash frequency and severity are largely independent across the six selected brands.
• BMW appears riskiest on severity, despite not leading in total crash count.
• Acura and Lexus show higher crash exposure but comparatively lower severity, which may make them less risky than raw crash counts suggest.
• GMC is notable because it has fewer crashes overall but still a relatively elevated severe crash rate.

Hypotheses

• Some brands may be involved in different types of crashes: one brand may have many lower-impact incidents, while another has fewer but more serious crashes.
• Differences in vehicle design, driver profile, or usage context may influence severity more than total crash exposure alone.

Limitations / Potential Bias

• Crash counts are not normalized by how many of each brand are on the road, so higher crash volume may partly reflect higher market presence.
• Severe crash rate does not control for driver behavior, trip purpose, road type, or vehicle model differences within a brand.

Question 2