Using many valid instrumental variables has the potential to improve efficiency but makes the usual inference procedures inaccurate. We give corrected standard errors, an extension of Bekker to nonnormal disturbances, that adjust for many instruments. We find that this adjustment is useful in empirical work, simulations, and in the asymptotic theory. Use of the corrected standard errors in t-ratios leads to an asymptotic approximation order that is the same when the number of instrumental variables grows as when the number of instruments is fixed. We also give a version of the Kleibergen weak instrument statistic that is robust to many instruments.

The demographic composition of the U.S. labor force has changed dramatically over the past several decades. My Dissertation examines the age distribution, the supply of skills, and the participation of women in the workforce. The Örst chapter postulates a connection between the age distribution and the business cycle. I develop an overlapping generations model featuring search frictions and productivity shocks to present the theory. Chapter 2 studies the supply of high-skill workers and also relies on a labor matching model. In the model, Örms react to changes in the distribution of skills by creating jobs designed speciÖcally for high-skill workers. The new matches are more proÖtable and less likely to break apart. In quantitative simulations, the model economies in the Örst two chapters replicate a substantial portion of the recent moderation in cyclical output volatility. The Öndings suggest an important role for demographics in determining the magnitude of aggregate áuctuations. The third chapter is joint work with Daniele Coen-Pirani and Alexis LeÛn. We estimate the e§ect of household appliance ownership on the labor force participation rate of married women using micro-level data. The di§usion of household appliances can account for about one-third of the increase in married womenís labor force participation rates observed during the 1960ís according to our results.

Different U.S. states have been affected by immigration to very different extents in recent years. Immigration increases available workers in a state economy and, because of its composition across education groups, it also increases the relative supply of less educated workers. However, immigration is more than a simple labor supply shock. It brings differentiated skills and more competition to the labor market and it may induce efficient specialization and affect the choice of techniques. Immigrants also affect investments, capital accumulation, and the productivity of more and less educated workers. Using a production function-based procedure and data on gross state product, physical capital and hours worked we analyze the impact of immigration on production factors (capital, more and less educated labor), and productivity over the period 1960-2006 for 50 U.S. states plus D.C. We apply growth accounting techniques to the panel of states in order to identify the changes in factors and productivity associated with immigration. To identify a causal impact we use the part of immigration that is determined by supply shifts in countries of origin and the geographical location of U.S. states or historical immigrants settlements. We find that immigration significantly increased the relative supply of less educated workers, that it did not affect much the level of capital per worker and that it significantly increased the productivity of highly educated workers and, even more, less educated workers. These channels together explain the small effect of immigrants on wages of less educated workers and the significant positive effects on wages of more educated workers.

Telecommuting is viewed as a public policy tool for reducing congestion and air pollution, but it may not be as effective as people think if workers who can telecommute choose to live (work) farther from their workplaces (homes) than non-telecommuters. Existing studies have not been able to fully address this issue because they all assume telecommuting is exogenous to commuting behavior. This study assembles information on telecommuting from the work schedule supplement to the May 2001 Current Population Survey (CPS) and information on commuting behavior from the 2000 Census 5% Public Use Micro-data Series (PUMS) and applies a two-sample instrumental variables technique to examining the impact of telecommuting on commute length and travel mode. I use the percent of workers who use the Internet when working at home in a person's two-digit occupation and MSA of the same size to instrument for telecommuting. The results show that telecommuting increases a married female worker's one-way commute time by 9-12 minutes. The impact on commute mode choice is positive and statistically insignificant.

In the mid-twentieth century, relative black wage growth in the North lagged behind the Jim Crow South. Inter-regional migration may explain this trend. Four million black southerners moved North from 1940 to 1970, more than doubling the northern black population. Black migrants will exert more competitive pressure on black wages if blacks and whites are imperfect substitutes. I use variation in the relative black-white migrant flows across skill groups to estimate the elasticity of substitution by race in the northern economy. I then calculate a counter-factual rate of black-white wage convergence in the North in the absence of southern migration. Migration slowed the pace of northern convergence by 50 percent, more than accounting for the regional gap. Ongoing migration appears to have been an impediment to black economic assimilation in the urban North.

While most studies of the decision to immigrate focus on the absolute income differences between countries, we argue that relative change in purchasing power or status, as captured by an individuals ranking in the wage distribution, may also be important. This will in turn be influenced by differential levels of supply, demand and migration costs across the skill distribution and across countries. Using data on Indian immigrants in the United States and the UK matched to comparable data on individuals who remained in India, we show that the average Indian immigrant will experience a fall in their relative ranking in the wage distribution compared to the position they would have achieved had they remained in the origin country. The fall in relative rankings is larger for immigrants to the UK than to the US, and largest of all for those with intermediate skills.

We analyze the behavioral responses of near-elderly males to unconditional grants of substantial cash disability benefits from the Veterans Administration's Disability Compensation (DC) program. The largely unstudied DC program provides income and health insurance to approximately three million veterans of military service who have service-connected disabilities. In contrast to other federal disability programs, receipt of DC benefits depends only on a veteran's diagnoses and is not contingent upon labor force status; thus, analysis of the behavioral responses to the DC program may inform economic understanding of the incentive and non-incentive effects of receipt of transfer income. We analyze these behavioral effects on the labor force participation of veterans, as well as their spillovers to claims on other federal benefits programs. We study a unique policy change, the 2001 Agent Orange decision, which expanded eligibility for DC benefits to a broader set of covered conditions-in particular, type II diabetes-to Vietnam veterans who had served in-theater (with 'Boots on the Ground' or BOG). Notably, the Agent Orange policy excluded Vietnam era veterans who did not serve in-theatre ('Not on Ground' or NOG), thus allowing us to assess the causal affects of DC edibility by contrasting the outcomes of BOG and NOG veterans. We find clear evidence that the increase in DC enrollment caused by the 2001 policy change had a significant negative effect on the labor supply of Vietnam veterans who had Boots on the Ground. Almost thirty percent of individuals who became eligible for the DC program dropped out of the labor force. The policy change also had an effect on enrollment in benefits programs administered by the Social Security Administration. Most notably, it raised SSDI enrollment among veterans who became newly eligible for DC benefits by a full percentage point. We also find suggestive evidence of spillovers from DC to both SSI and OASI benefits. Our ongoing work analyzes in detail the causal channels through which these labor supply and programmatic responses operate.

The Great Depression is a prime example of a macroeconomic crisis that produced adverse economic and social effects in all spheres of life. The theoretical arguments about the real effects of the Great Depression on education vary. The first is that of economic hardships, which might force individuals eligible to go to school to work for their sustenance. The second argument is that high unemployment would reduce the opportunity cost of going to school, making going to school the best other viable alternative. Following these theoretical notions, this paper explores the impact of the Great Depression on education, on race (whites and blacks) and gender (males and females), during the period from 1930 to 1940. Furthermore, this paper examines the effects of state employment indices on the average education (at the mean). The results (using individual census data from 1960) show some evidence that the Great Depression affected education of whites born between 1911 and 1915. However, the results show no evidence that the variation in state employment indices affected the decision of schooling on the average (mean), but it affected the education of white males at the top of the distribution (90% percentile).

The influence of religion on family size in late nineteenth/early twentieth century Ontario is examined using a set of 7,156 census-linked probated decedents. Religion can directly shape values and attitudes towards fertility as well as provide social contacts and networks that encourage child bearing. As well, religion can indirectly affect wealth and fertility because of differences towards fertility, childrearing and education. A simple model of children in an old age security framework is presented, which is then translated into a reduced form econometric model with a comprehensive set of variables including religious affiliation. While empirical studies using historical Canadian micro-data have found only a weak relationship between religious affiliation and the number of children, these results find statistically significant relationships. However, they do not fall into the liberal-conservative divide of other North American studiessuggesting that the effect of religion on family size and fertility is considerably more complex.

In this paper we examine educational disparities in mortality and life expectancy among non-Hispanic blacks and whites in the 1980s and 1990s. Despite increased attention and substantial dollars directed to groups with low socioeconomic status, within race and gender groups, the educational gap in life expectancy is rising, mainly because of rising differentials among the elderly. With the exception of black males, all recent gains in life expectancy at age twenty-five have occurred among better-educated groups, raising educational differentials in life expectancy by 30 percent. Differential trends in smoking related diseases explain at least 20 percent of this trend.

The literature on immigration policies/quotas in terms of human capital has been growing in the last decade. Typically immigration policies in this literature tend to be monotonic filters, i.e. they favor immigrantsoverrepresentation at the top or bottom of the skill spectrum but neither the middle nor both, top and bottom. We provide some evidence on the lack of this monotonicity in the data and propose one explanation.

We examine changes in the characteristics of American youth between the late 1970s and the late 1990s, with a focus on characteristics that matter for labor market success. We reweight the NLSY79 to look like the NLSY97 along a number of dimensions that are related to labor market success, including race, gender, parental background, education, test scores, and variables that capture whether individuals transition smoothly from school to work. We then use the re-weighted sample to examine how changes in the distribution of observable skills affect employment and wages. We also use more standard regression methods to assess the labor market consequences of differences between the two cohorts. Overall, we find that the current generation is more skilled than the previous one. Blacks and Hispanics have gained relative to whites and women have gained relative to men. However, skill differences within groups have increased considerably and in aggregate the skill distribution has widened. Changes in parental education seem to generate many of the observed changes.

College-educated workers are twice as likely as high school graduates to make lasting long distance moves, but little is known about the role of college itself in determining geographic mobility. Unobservable characteristics related to selection into college might also drive the relationship between college education and geographic mobility. We explore this question using a number of methods to analyze both the 1980 Census and longitudinal sources. We conclude that the causal impact of college completion on subsequent mobility is large. We introduce new instrumental variables that allow us to identify educational attainment and veteran status separately in a sample of men whose college decisions were exogenously influenced by their draft risk during the Vietnam War. Our preferred IV estimates imply that graduation increases the probability that a man resides outside his birth state by approximately 35 percentage points, a magnitude nearly twice as large as the OLS migration differential between college and high school graduates. IV estimates of graduations impact on total distance moved are even larger, with IV estimates that exceed OLS considerably. We provide evidence from the National Longitudinal Survey of Youth (NLSY) 1979 that our large IV estimates are plausible and likely explained by heterogeneous treatment effects. Finally, we provide some suggestive evidence on the mechanisms driving the relationship between college completion and mobility.

his dissertation consists of three chapters on the youth and low-skilled labor markets. In Chapter 1, I show that teen employment is significantly more responsive than adult employment to immigration, and that growth in low-skilled immigration appears to be a partial explanation for recent declines in teen employment rates. Using variation in immigrant shares across metropolitan areas between 1980 and 2000, I demonstrate that the impact of immigration on youth employment is at least twice as large as the impact on adults, and that immigration affects school enrollment decisions and the type of jobs held by native youth. These effects are strongest for black youth and youth from poorer and less educated families. The estimates suggest that a 10 percentage point increase in the immigrant share of a city's low-skilled population reduces the teen employment rate by 5 percentage points, implying that between one-third and one-half of the fall in teen employment between 1990 and 2005 can be explained by increased immigration. In Chapter 2, co-authored with David H. Autor and Alan Manning, we offer a fresh analysis of the effect of state and federal minimum wages on earnings inequality over 1979 to 2007, exploiting substantially longer state-level wage panels than were available to earlier analyses as well as a proliferation of recent state minimum wage laws. We obtain identification using cross-state and over-time variation in the 'bite' of federal and applicable state minimum wages, as per influential studies by Lee (1999) and Teulings (2000, 2003).

This article investigates the recent rise of criminal background screening in rental housing as a case study of the diffusion of actuarial social control. That case study suggests that actuarial techniques have spread more widely through the crime prevention field than sociolegal scholars have recognized, replacing disciplinary efforts to diagnose and alter the behavior of individuals with actuarial efforts to identify and isolate high-risk groups. This actuarial strategy has proliferated not only because new discourses encouraged it but also because new institutional structures facilitated it. That conclusion illustrates the importance of structural (rather than cultural) factors in shaping societys response to crimeparticularly the growing availability of the collective institutional capacity that actuarial social control requires.