Queen's University Lemieux belongs to the world's foremost labour economists in terms of research output, in particular on wage inequality.
[4] Thomas Lemieux's research interests mostly relate to labour economics in general and wage inequality in specific as well as econometric methods to analyze these issues.
[13][14] In another study with Card, Lemieux suggested that falling supply in highly educated workers may account for the growth in the return to college for younger men in the U.S., UK and Canada.
[15] In the 2000s, Lemieux repeatedly highlighted the role of increased returns to postsecondary education and sophisticated institutional explanations (e.g. including performance pay, based on work with Bentley MacLeod and Daniel Parent) for the growth in wage inequality at the top of the wage distribution in the 1980s and 1990s, while arguing against simple models of skill-biased technological change[16][17][18][19] This empirical discussion was accompanied by various models advanced by Lemieux, e.g. - in joint work with Robert Gibbons, Lawrence Katz and Parent - of a model where a worker's skills are imperfectly observable but determine her current wage and sector, high-skill workers concentrate in high-wage sectors, thus earning high returns to their skills (with Robert Gibbons, Lawrence Katz and Daniel Parent).
[22] Publications with Guido Imbens and David S. Lee, Lemieux further reviewed the use of regression discontinuity designs in economics[23] and provides guidance for practitioners.
[24] Another key area of Lemieux's work in econometrics are decomposition methods, in particular related to comparisons between wage distributions and the analysis of their dynamics.
[30] Other major research by Lemieux includes an analysis of the effects of foreign competition on Canadian collective bargaining agreements (with John Abowd),[31] of the effects of taxes on informal labour supply (with Bernard Fortin and Pierre Frechette),[32] on the evolution of work, school and living arrangements among North American youth in the 1970s-90s,[33] on the substitution of alcohol by marijuana due to the increase in the minimum drinking age in several U.S. states,[34] and on dropout and enrollment trends in the U.S. in the postwar period.