Slow Magic: Agricultural Versus Industrial R&D Lag Models

R&D is slow magic. It takes many years before research investments begin to affect productivity, but then they can affect productivity for a long time. Many economists get this wrong. Here, we revisit the conceptual foundations for R&D lag models used to represent the temporal links between research investments and impact, review prevalent practice, and document and discuss a range of evidence on R&D lags in agriculture and other industries. Our theory and evidence consistently support the use of longer lags with a different overall lag profile than is typically imposed in studies of industrial R&D and government compilations of R&D knowledge stocks. Many studies systematically fail to recognize the many years of investment and effort typically required to create a new technology and bring it to market and the subsequent years as the technology is diffused and adopted. Consequential distortions in the measures and economic understanding are implied. Expected final online publication date for the Annual Review of Resource Economics, Volume 15 is October 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.