Todd's primary areas of interest are the study of migration issues and the study of firm market power over workers. His recent work has shown that firm wage setting power increases during economic downturns and that firm market power may bias estimates of the substitutability of different types of workers. He has also studied the mobility of guest workers on H-1B visas and found a surprising amount of mobility of these workers, providing a check on firm market power over these workers.

He joined IZA as a Research Affiliate in January 2007 and became a Research Fellow in April 2010.



IZA Discussion Paper No. 10646
Nathan Wiseman, Todd A. Sorensen

Instrumental variables (IV) is an indispensable tool for establishing causal relationships between variables. Recent work has focused on improving bounds for cases when an ideal instrument does not exist. We leverage a principle, "Intransitivity in Correlations," related to an under-utilized property from the statistics literature. From this principle, it is...

IZA Discussion Paper No. 10558
Christian Neumeier, Todd A. Sorensen, Douglas A. Webber
forthcoming in: Southern Economic Journal

The explicit costs of raising a child have grown over the past several decades. Less well understood are the implicit costs of having a child, and how they have changed over time. In this paper we use longitudinal administrative data from over 70,000 individuals in the Synthetic SIPP Beta to...

IZA Discussion Paper No. 9668

We address the impact of declining migration on the measurement of labor market health. We first document an historically significant decline in the growth rate of the U.S. foreign born population since 2000. A decomposition shows that nearly two-thirds of the decline can be attributed to declining pull factors in...

IZA Discussion Paper No. 7456
forthcoming in: Journal of Population Economics

Critics of the H-1B program for high-skilled workers argue that the program restricts immigrant job mobility and lacks a vehicle for adjusting the number of visas during a recession. We study the job mobility of highly-skilled Indian IT guest workers and provide new evidence on their inter-firm mobility and return...

IZA Discussion Paper No. 5928
published in: Labour Economics, 2013, 24, 196-204

A body of recent empirical work has found strong evidence that the labor elasticity of supply to the firm is finite, implying that firms may have wage setting power. However, these studies capture only snapshots of the parameter. We study this parameter over a period that provides substantial variation in...

IZA Discussion Paper No. 5881
published in: Southern Economic Journal, 2014, 80 (3), 772-782. Winner of 2015 Georgescu-Roegen Prize for best paper published in SEJ during the calendar year.

In this paper we explore the impact of imperfectly competitive input markets on production function estimation. First order profit maximizing conditions are altered when frictions in input markets cause the elasticity of input supply to the firm to be finite. A consequence of this is that the standard econometric model...

IZA Discussion Paper No. 5492

We present estimates of the effect of legal immigration status on earnings of undocumented workers. Our contribution to the literature centers on a two-step procedure that allows us to first estimate the legal status of an immigrant and then estimate the effect of the Immigration Reform and Control Act (IRCA)...

IZA Discussion Paper No. 3301
published as 'Mexican Immigrants, Labour Market Assimilation and the Current Population: The Sensitivity of Results Across Seemingly Equivalent Surveys' in: International Migration, 2015, 53(2), 250–262

In this paper we compare estimates of immigrants’ labor supply assimilation profiles using the Current Population Survey Annual Demographic Files (March ADS) and the Current Population Survey Outgoing Rotation Groups (ORGs). We use a measure that is seemingly consistent across both surveys: usual weekly hours of work in the main...

IZA Discussion Paper No. 3060

During the 1930s the federal government embarked upon an ambitious series of grant programs designed to counteract the Great Depression. Public works and relief programs combated unemployment by hiring workers and building social overhead capital while the Agricultural Adjustment Administration (AAA) sought to raise farm incomes by paying farmers not...

IZA Discussion Paper No. 2870
revised version published as 'Race and Gender Differences under Federal Sentencing Guidelines' in: American Economic Review , 2012, 102 (3), 256–260.

The Federal criminal sentencing guidelines struck down by the U.S. Supreme Court in 2005 required that males and females who commit the same crime and have the same prior criminal record be sentenced equally. Using data obtained from the United States Sentencing Commission’s records, we examine whether there exists any...