In his youth, the economist Kenneth Arrow analysed weather forecasts for the US Army. When he found that the predictions were as reliable as historical averages, he suggested reallocating manpower. The response from the army general’s office? “The general is well aware that your division’s forecasts are worthless. However, they are required for planning purposes.”
Even before COVID-19, many shared that scepticism of forecasts. The failure to foresee the 2008-09 financial crisis started a debate on economic modelling. Over the past year, the performance of epidemiological models has not resolved this quandary.
Investors have long known that “all models are wrong, but some are useful,” to use the statistician George Box’s pithy idiom. But, there are modellers who use this defence to preserve models beyond usefulness. Meanwhile, there are unrealistic expectations from consumers of models including investors, policymakers and society. They assume that complex issues are easy to forecast, when some things are just unknowable. This gap begs the question of what investors should do.
Author(s): Sahil Mahtani
Publication Date: April 2021
Publication Site: Investments & Pensions Europe