The claim that medical error is the third leading cause of death in the US has been zooming around the internet for years.

This would mean that only heart disease and cancer killed more people than the very people trying to treat these diseases.

But there are good reasons to be suspicious about the claim.

Professor Mary Dixon-Woods, director of The Healthcare Improvement Studies Institute, or THIS Institute, at Cambridge University, explains what’s going on.

Presenter: Tim HarfordSeries producer: Tom CollsProduction coordinator: Brenda BrownSound mix: Nigel Appleton Editor: Richard Vadon