McNamara fallacy

The ‘McNamara fallacy’ (also known as quantitative fallacy) is named after the US Secretary of Defense during the Vietnam War. The fallacy consists of over-reliance on metrics, and may be summarised as: ‘if it cannot be measured, it is not important’. This paper describes the McNamara fallacy as it applies to medicine and healthcare, taking as examples hospital mortality data, NHS targets and quality assurance.