Does Europe's flat productivity gap reflect a shifting price yardstick?
Core argument: European productivity growth has trailed the United States for three decades, a point on which both Krugman and the authors agree, with Krugman stating explicitly that he is not arguing European productivity is mismeasured.
Krugman and we agree that (1) European productivity growth has trailed the United States for three decades, and Krugman says so clearly (”I am not arguing that European productivity is mismeasured, and never said that.”) (2) Current-PPP chain and a national deflator answer different questions. (3) The weighting mechanism by which an economy that produces goods with falling relative prices sees part of its volume gain valued away, is part of the channel to explain the paradox. We disagree still on one crucial question: Krugman reads the flat current-PPP line as evidence that Europe is not falling behind, while we see it as the product of moving the price measurement stick every year. Hence we do not see the current- PPP line as indicative of anything interpretable.

