arXiv subjects

David Roodman

Publications and source records attributed to David Roodman.

11 recordsLinked to original sources

arXiv2026

An evidence review of worker retraining

We review the evidence on subsidized job training programs in industrial countries. We provide critical, narrative summaries of randomized studies of major job training in the US; of two "judge randomization" studies in the US and Denmark; and of previous meta-analyses. We then perform a meta-analysis of 56 randomized trials of job training in the US since 1973, the most exhaustive meta-analysis in this niche. Here, average impacts are positive but modest: employment rises 1.7 percentage points in years 3-5, and annual pre-tax earnings by roughly \$800 per person offered training. At an average cost of \$13,598 per participant, programs roughly break even under (debatable) assumptions about how long benefits persist. They recoup about three-quarters of their cost for government through higher tax revenue and lower benefit use. Evaluations of the largest federal efforts--JTPA, the Workforce Investment Act, and Job Corps--return small or null effects. One cluster of programs stands out: "sector programs," which screen applicants intensively, design curricula with employers, and track local skill demand. They raise earnings roughly ten times as much. They have proven difficult to replicate.

econ.GN↗

arXiv2026

On the probability distribution of long-term changes in the growth rate of the global economy: An outside view

Daniel Kahneman and Amos Tversky argued for challenging inside views (informed by contextual specifics) with outside views (based on historical "base rates" for certain event types). A reasonable inside view of the prospects for the global economy in this century is that growth will converge to 2.5%/year or less: population growth is expected to slow or halt by 2100; and as more countries approach the technological frontier, economic growth should slow as well. To test that view, this paper models gross world product (GWP) observed since 10,000 BCE or earlier, in order to estimate a base distribution for changes in the growth rate as a function of the GWP level. For econometric rigor, it casts a GWP series as a sample path in a stochastic diffusion whose specification is novel yet rooted in neoclassical growth theory. After estimation, most observations fall between the 40th and 60th percentiles of predicted distributions. The fit implies that GWP explosion is all but inevitable, in a median year of 2047. The friction between inside and outside views highlights two insights. First, accelerating growth is more easily explained by theory than is constant growth. Second, the world system may be less stable than traditional growth theory and the growth record of the last two centuries suggest.

econ.GN↗

arXiv2024

Julia as a universal platform for statistical software development

The julia package integrates the Julia programming language into Stata. Users can transfer data between Stata and Julia, issue Julia commands to analyze and plot, and pass results back to Stata. Julia's econometric ecosystem is not as mature as Stata's or R's or Python's. But Julia is an excellent environment for developing high-performance numerical applications, which can then be called from many platforms. For example, the boottest program for wild bootstrap-based inference (Roodman et al. 2019) and fwildclusterboot for R (Fischer and Roodman 2021) can use the same Julia back end. And the program reghdfejl mimics reghdfe (Correia 2016) in fitting linear models with high-dimensional fixed effects while calling a Julia package for tenfold acceleration on hard problems. reghdfejl also supports nonlinear fixed-effect models that cannot otherwise be fit in Stata--though preliminarily, as the Julia package for that purpose is immature.

econ.EM↗

arXiv2024

Long-term Effects of India's Childhood Immunization Program on Earnings and Consumption Expenditure: Comment

Summan, Nandi, and Bloom (2023), hereafter SNB, find that exposure during infancy to India's Universal Immunization Programme (UIP) increased wages and per-capita household expenditure in early adulthood. SNB regress these outcomes on a treatment indicator that depends upon year and district of birth while controlling for age at follow-up. Because year of birth and age are nearly collinear, SNB's identifying variation does not come from the staggered introduction of the UIP, but rather from the progression of time during the follow-up period. Within the 12-month follow-up period, those interviewed later were more likely to have been treated and, on average, reported higher wages and household expenditure. Wages and household expenditure, however, rose by at least as much in a control group composed of people too old to have been exposed as infants to the UIP as in the treated group. SNB's results are best explained by inflation, economic growth, and non-random survey sequencing during the follow-up survey period.

econ.GN↗

arXiv2024

The Arrival of Fast Internet and Employment in Africa: Comment

Hjort and Poulsen (2019) frames the staggered arrival of submarine Internet cables on the shores of Africa circa 2010 as a difference-in-differences natural experiment. The paper finds positive impacts of broadband on individual- and firm-level employment -- with a bias toward skilled employment -- and on nighttime light emissions. These results largely are not robust to alternative geocoding of survey locations, to correcting for a satellite changeover at end-2009, and to revisiting a definition of the treated zone that has no clear technological basis, is narrower than the spatial resolution of nearly all the data sources, and is empirically suboptimal as a representation of the geography of broadband.

econ.GN↗

arXiv2023

Large-Scale Education Reform in General Equilibrium: Regression Discontinuity Evidence from India: Comment

Mainly through regression discontinuity designs, Khanna (2023a) studies the impacts of a primary schooling expansion in India in the 1990s. Absent from the data set are four districts close to the modeled treatment discontinuity. Incorporating them cuts the impact of intention to treat on schooling attainment by two-thirds and the impact on wages by a third. Methodological revisions, including clustering by the geographic unit of treatment, double or triple standard errors, bringing estimates within a standard error of zero. These findings are robust to varying the location of the discontinuity, the bandwidth, and the radius of an exclusionary "donut." The estimates of the general equilibrium effect on the skill premium, as well as elasticities of substitution across age and skill groups, have high variance. One cause is that the treatment discontinuity does not occur quite where modeled. Moving the assumed cutoff pro-duces sharper but wrong-signed results.

econ.GN↗

arXiv2022

Schooling and Labor Market Consequences of School Construction in Indonesia: Comment

Duflo (2001) exploits a 1970s schooling expansion in Indonesia to estimate impacts on schooling and labor outcomes, as well as the returns to schooling. I correct data errors, adjust for potential sources of bias, follow up later in life, and check sensitivity to two specification choices that are not explained in the original text and that are applied to some regressions and not others. Headline estimates from the original, 1995 follow-up are generally not robust to the revisions. Returns to schooling are weakly identified. But certain "fingerprints" from Duflo (2001) specification checks--impacts appearing only in the birth cohorts or at the grade levels where expected--recognizably persist. E.g., impact estimates from kink-based specifications that focus on timing by birth cohort are consistently positive, if not always at conventional significance lev-els. The best explanation, though weakened, is causation from the schooling expansion to individual schooling attainment to wages.

econ.GN↗

arXiv2020

The impacts of incarceration on crime

This paper reviews the research on the impacts of incarceration on crime. Where data availability permits, reviewed studies are replicated and reanalyzed. Among three dozen studies I reviewed, I obtained or reconstructed the data and code for eight. Replication and reanalysis revealed significant methodological concerns in seven and led to major reinterpretations of four. I estimate that, at typical policy margins in the United States today, decarceration has zero net impact on crime outside of prison. That estimate is uncertain, but at least as much evidence suggests that decarceration reduces crime as increases it. The crux of the matter is that tougher sentences hardly deter crime, and that while imprisoning people temporarily stops them from committing crime outside prison walls, it also tends to increase their criminality after release. As a result, "tough-on-crime" initiatives can reduce crime in the short run but cause offsetting harm in the long run. A cost-benefit analysis finds that even under a devil's advocate reading of this evidence, in which incarceration does reduce crime in U.S., it is unlikely to increase aggregate welfare.

econ.GN↗

arXiv2020

The domestic economic impacts of immigration

This paper critically reviews the research on the impact of immigration on employment and wages of natives in wealthy countries--where "natives" includes previous immigrants and their descendants. While written for a non-technical audience, the paper engages with technical issues and probes one particularly intense scholarly debate in an appendix. While the available evidence is not definitive, it paints a consistent picture. Industrial economies can generally absorb migrants quickly, in part because capital is mobile and flexible, in part because immigrants are consumers as well as producers. Thus, long-term average impacts are probably zero at worst. And the long-term may come quickly, especially if migration inflows are predictable to investors. Possibly, skilled immigration boosts productivity and wages for many others. Around the averages, there are distributional effects. Among low-income "native" workers, the ones who stand to lose the most are those who most closely resemble new arrivals, in being immigrants themselves, being low-skill, being less assimilated, and, potentially, undocumented. But native workers and earlier immigrants tend to benefit from the arrival of workers different from them, who complement more than compete with them in production. Thus skilled immigration can offset the effects of low-skill immigration on natives and earlier immigrants.

econ.GN↗

arXiv2020

The impacts of alcohol taxes: A replication review

This paper reviews the research on the impacts of alcohol taxation outcomes such as heavy drinking and mortality. Where data availability permits, reviewed studies are replicated and reanalyzed. Despite weaknesses in the majority of studies, and despite seeming disagreements among the more credible one--ones based on natural experiments--we can be reasonably confident that taxing alcohol reduces drinking in general and problem drinking in particular. The larger and cleaner the underlying natural experiment, the more apt a study is to detect impacts on drinking. Estimates from the highest-powered study settings, such as in Alaska in 2002 and Finland in 2004, suggest an elasticity of mortality with respect to price of -1 to -3. A 10% price increase in the US would, according to this estimate, save 2,000-6,000 lives and 48,000-130,000 years of life each year.

econ.GN↗

arXiv2020

The impact of life-saving interventions on fertility

Many interventions in global health save lives. One criticism sometimes lobbed at these interventions invokes the spirit of Malthus. The good done, the charge goes, is offset by the harm of spreading the earth's limited resources more thinly: more people, and more misery per person. To the extent this holds, the net benefit of savings lives is lower than it appears at first. On the other hand, if lower mortality, especially in childhood, leads families to have fewer children, life-saving interventions could reduce population. This document critically reviews the evidence. It finds that the impact of life-saving interventions on fertility and population growth varies by context, and is rarely greater than 1:1. In places where lifetime births/woman has been converging to 2 or lower, saving one child's life should lead parents to avert a birth they would otherwise have. The impact of mortality drops on fertility will be nearly 1:1, so population growth will hardly change. In the increasingly exceptional locales where couples appear not to limit fertility much, such as Niger and Mali, the impact of saving a life on total births will be smaller, and may come about mainly through the biological channel of lactational amenorrhea. Here, mortality-drop-fertility-drop ratios of 1:0.5 and 1:0.33 appear more plausible. But in the long-term, it would be surprising if these few countries do not join the rest of the world in the transition to lower and more intentionally controlled fertility.

econ.GN↗