Population projections: why they are often wrong

As an economist it is always nice to come across another profession that, for many good and legitimate reasons, struggles to always make accurate predictions of the future; hello demographers. Predicting the size and composition of future populations is a fundamentally important thing to do. Population projections underpin our estimates of future healthcare needs, government spending and tax revenues (and possible debt and deficits), housing demand, and road, rail, and air transport needs. The list isn’t endless, but it’s certainly long. It’s perhaps unfortunate then that it turns out that population projection is quite a difficult thing to do and one which we repeatedly get wrong.

Demographers who construct population projections know how difficult it is …