Seat-belts usage and analogies

Analogies can be useful for explaining statistics.

A journalist from the Financial Times spoke to me about vaccination statistics. I used an analogy to help explain why the vaccinated share of deaths rises as coverage grows:

About two-thirds of people who die on UK roads are wearing a seatbelt, but this is a consequence of usage rates of nearly 99 per cent, Masters said. He added that the same logic applied to severe disease and death in highly vaccinated populations.

These figures are imprecise. What I recall saying was:

In Great Britain, most car occupants who die in incidents are wearing seat-belts. It is a reflection seat-belt usage is very high but are not a perfect protection.

The sub-editor appears to have translated my description into numbers. On reflection, I should have offered better estimates. The claim is about car occupants in Great Britain.

The Department for Transport produces reports for road casualties in Great Britain. The 2019 report has an accompanying datasheet, showing:

• Percentage of car occupants killed who were not wearing a seat belt.