Thomas Mroz

Andrew Young School of Policy Studies
33 Gilmer St SE
Atlanta, GA 30302
Tel: 864-656-3142

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
Institutional Affiliation: Clemson University

NBER Working Papers and Publications

June 2015Sample-selection biases and the “industrialization puzzle”
with Howard Bodenhorn, Timothy W. Guinnane: w21249
Understanding long-term changes in human well-being is central to understanding the consequences of economic development. An extensive anthropometric literature purports to show that heights in the United States declined between the 1830s and the 1890s, which is when the US economy industrialized and urbanized. Most research argues that declining heights reflects the impact of the industrialization process. This interpretation, however, relies on sources subject to selection bias. Changes in that selection mechanism may account for the declining heights. We show that the evidentiary basis of the puzzle is not as robust as previously believed. Our meta-analysis of more than 150 studies shows that declining-heights finding emerges primarily in selected samples. Finally, we offer a parsimoni...

Published: Bodenhorn, Howard & Guinnane, Timothy W. & Mroz, Thomas A., 2017. "Sample-Selection Biases and the Industrialization Puzzle," The Journal of Economic History, Cambridge University Press, vol. 77(01), pages 171-207, March. citation courtesy of

March 2014Caveat Lector: Sample Selection in Historical Heights and the Interpretation of Early Industrializing Economies
with Howard Bodenhorn, Timothy Guinnane: w19955
Much of the research on height in historical populations relies on convenience samples. A crucial question with convenience samples is whether the sample accurately reflects the characteristics of the population; if not, then estimated parameters will be affected by sample selection bias. This paper applies a simple test for selection biased developed in Bodenhorn, Guinnane, and Mroz (2013) to several historical samples of prisoners, freed slaves, and college students. We reject the hypothesis of no selection bias in all cases. Using Roy's (1951) model of occupational choice, we interpret these findings as reflecting the economic forces that lead individuals to take the actions the led to inclusion in the sample. Our findings suggest that much of the evidence on the "industrialization pu...
October 2000Estimating the Effects of Covariates on Health Expenditures
with Donna B. Gilleskie: w7942
This paper addresses estimation of an outcome characterized by mass at zero, significant skewness, and heteroscedasticity. Unlike other approaches suggested recently that require retransformations or arbitrary assumptions about error distributions, our estimation strategy uses sequences of conditional probability functions, similar to those used in discrete time hazard rate analyses, to construct a discrete approximation to the density function of the outcome of interest conditional on exogenous explanatory variables. Once the conditional density function has been constructed, we can examine expectations of arbitrary functions of the outcome of interest and evaluate how these expectations vary with observed exogenous covariates. This removes a researcher's reliance on strong and often un...

Published: Gilleskie, Donna and Thomas A. Mroz. “A Flexible Approach for Estimating the Effects of Covariates on Health Expenditures.” Journal of Health Economics 23, 2 (2004): 391-418.

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