This chapter discusses common methodological, theoretical and empirical choices that scholars face when undertaking productive and economic efficiency analyses. After summarizing the main results of duality theory in Section 2, we outline in Section 3 the most popular empirical methods available...

Most papers on returns to languages are concerned with immigrants. We use the European Community Household Panel Survey (ECHP) to infer returns on non-native languages by non-immigrants in nine countries of the European Union. We differ from the few other studies that deal with the same problem...