The shape of aggregate production functions: evidence from estimates of the World Technology Frontier

The article provides multifaceted evidence on the shape of the aggregate country-level production function, derived from the World Technology Frontier, estimated on the basis of annual data on inputs and output in 19 highly developed OECD countries in the period 1970–2004. A comparison of its estimates based on Data Envelopment Analysis and Bayesian Stochastic Frontier Analysis uncovers a number of significant discrepancies between the nonparametric estimates of the frontier and the Cobb–Douglas and translog production functions in terms of implied efficiency levels, partial elasticities, and returns-to-scale properties. Furthermore, the two latter characteristics as well as elasticities of substitution are found to differ markedly across countries and time, providing strong evidence against the constant-returns-to-scale (CRS) Cobb–Douglas specification, frequently used in related literature. We also find notable departures from perfect substitutability between unskilled and skilled labor, consistent with the hypotheses of skill-biased technical change and capital–skill complementarity. In the Appendix, as a corollary from our results, we have also conducted a series of development accounting and growth accounting exercises.world technology frontier, aggregate production function, Data Envelopment Analysis, Stochastic Frontier Analysis, partial elasticity, returns to scale, substitutability

FIGO classification for the clinical diagnosis of placenta accreta spectrum disorders

© 2019 International Federation of Gynecology and ObstetricsPlacenta accreta spectrum is impacting maternal health outcomes globally and its prevalence is likely to increase. Maternal outcomes depend on identification of the condition before or during delivery and, in particular, on the differential diagnosis between its adherent and invasive forms. However, accurate estimation of its prevalence and outcome is currently problematic because of the varying use of clinical criteria to define it at birth and the lack of detailed pathologic examination in most series. Adherence to this new International Federation of Gynecology and Obstetrics (FIGO) classification should improve future systematic reviews and meta-analyses and provide more accurate epidemiologic data which are essential to develop new management strategies.info:eu-repo/semantics/publishedVersio