On the Measurement of Growth Over the Long Run

Methodologies for the construction of national accounts often differ across time and countries. This paper discusses issues raised by this methodological heterogeneity on the long-run measure of economic growth and presents two sets of internationally comparable estimates of GDP for the period from 1820 to 2018. The estimates are based on real product benchmarks relative to a reference economy. The reference economy’s GDP time series is a normalized composite of several indices. The US and the UK are used as reference economies producing two sets of estimates. These estimates suggest less variation in incomes among developed economies than those of the 2018 version of the Maddison Project, are closer to Maddison’s original estimates, and suggest that both these datasets underestimated growth in the more distant past relative to more recent decades.