Please, no more projections. What we need are predictions, and they're harder

19 Nov 2019

For The Conversation: Professor John Quiggin explains the difference between projections and predictions, and makes a case for the superiority of predictions. 

This is an image of a graph on a computer screenThe difficulty of making predictions has long been known, but the rise of the internet means that it is getting harder to hide the gaps between predictions and reality.

Perhaps the most significant example of repeated failed projections has been the International Energy Agency’s projections of the importance of renewable power – the proportion of electricity generated by solar and wind and other renewable sources other than hydro.

Beginning in 1994, when generation from these sources was negligible, the Agency has produced estimates of the future share of renewables every two years.

Every two years, with striking regularity, the previous estimates have been exceeded (hugely) and the new set has been revised upwards. But never by enough. Each time the upward revision has been inadequate.