How old is the data Britain runs on?

The fast indicators are the ones that fall out of running a system. A hospital records an appointment because it has to schedule it. The Treasury knows what it borrowed because it borrowed it. A prison counts the people in it every week. That data arrives monthly or weekly because collecting it is inseparable from the operation itself.

The slow indicators mostly come from surveys and registrations: household income, food insecurity, mental health prevalence, healthy life expectancy. Somebody has to decide to ask, fund the asking, wait for fieldwork, and process the answers. The psychiatric morbidity survey behind the mental health indicator runs roughly every seven years, which is why the newest figure is 29 months old.

The consequence is a system that sees its own throughput in near real time and the condition of the population late. Waiting lists, borrowing and prison capacity are visible fast enough to manage week to week. Whether children are poorer, whether people are dying earlier, whether housing costs have outrun incomes, arrive a year or two after the fact, by which point the policy that caused the movement may itself be two governments old.