Just to be clear, we need to measure inflation, and therefore, by accident, we end up measuring productivity. Here is a simplified example: The nominal money G

Just to be clear, we need to measure inflation, and therefore, by accident, we end up measuring productivity. Here is a simplified example: The nominal money GDP increases by 6% Population increases by 1.5% That leaves 4.5% that is either inflation or productivity. If we determine that inflation was 3% then we know that productivity grew by 1.5%. We don't necessarily aim to measure productivity (I mean, we do, but even if we did not) we would still end up with a productivity number, once we had subtracted out population growth and inflation.