Since COVID-19, a narrative about economic stagnation in Europe alongside booming productivity in America — “Eurosclerosis,” to use an old but newly fashionable term — has attained the status of accepted fact in discussions of global politics. Though analysts may differ about what conclusions to draw or what steps should be taken, the “fact” itself is seldom questioned.

Since all of the relevant numbers on this subject come from a handful of marquee statistical series produced by leading international organizations — and since they’re all constantly scrutinized and litigated by legions of economists and policy experts — you might think the raw facts contained in them would be a settled question. But there’s a serious problem lurking in these data, one that seems to have gone entirely unnoticed in the discourse.

To compare gross domestic product (GDP) levels between countries, raw monetary figures — like the UK’s 2024 GDP of £2.9 trillion or the United States’ $29.2 trillion — have to be converted to a common unit of measure. This is typically done using purchasing power parities (PPPs), which are like ordinary exchange rates, but adjusted for differences in national price levels.