Christopher L. Smith

The Contribution of the Minimum Wage to US Wage Inequality over Three Decades: A Reassessment

We reassess the effect of minimum wages on US earnings inequality using additional decades of data and an IV strategy that addresses potential biases in prior work. We find that the minimum wage reduces inequality in the lower tail of the wage distribution, though by substantially less than previous estimates, suggesting that rising lower tail inequality after 1980 primarily reflects underlying wage structure changes rather than an unmasking of latent inequality. These wage effects extend to percentiles where the minimum is nominally nonbinding, implying spillovers. We are unable to reject that these spillovers are due to reporting artifacts, however. (JEL J22, J31, J38, K31)

The Sources and Uses of Annual Giving at Selective Private Research Universities and Liberal Arts Colleges.

Abstract Selective private research universities and liberal arts colleges differ in the shares of their annual giving coming from different sources (alumni, other individuals, foundations, corporations) and the shares of their annual giving applied to different uses (current operations, buildings and equipment, enhancing their endowments). After providing background data on the aggregate variation in these shares over time and their variation across institutions at a point in time, our econometric analyses use data from a panels of selective private research universities and liberal arts colleges that span a 31-year period to provide explanations for differences across institutions in the sources and uses of giving. These differences are seen to depend upon a number of institutional characteristics. One key finding is that richer institutions, as measured by endowment per student, devote a larger share of their annual giving to further building their endowments. This contributes to the increasing dispersion of wealth across private academic institutions.

Analyzing the success of student transitions from 2- to 4-year institutions within a state

Abstract Multiple 2- and 4-year public institutions exist within many states in the United States. Our paper develops a methodology that can be used to help evaluate how each 2-year public institution in a state is doing in preparing those of its students who transfer to 4-year public institutions in the state to successfully complete 4-year programs. Similarly the methodology can be used to help evaluate how well each 4-year public institution in the state is doing in educating and graduating those students from 2-year public institutions that transfer to it. The methodology is illustrated using date provided by the Office of Institutional Research and Analysis of the State University of New York.

Influence of hypercortisolemia on soluble tumor necrosis factor receptor II and interleukin-1 receptor antagonist responses to endotoxin in human beings

BACKGROUND We have previously reported that the antecedent administration of glucocorticoids altered both the hormonal and proinflammatory cytokine responses to lipopolysaccharide (LPS) when administered to human volunteers. In that study, subjects with vastly exaggerated levels of tumor necrosis factor (TNF) and interleukin (IL)-6 12 and 144 hours after cortisol infusion exhibited hemodynamic and hormonal responses no different from those of untreated subjects after endotoxin. The current study examined levels of the antiinflammatory cytokines interleukin-1 receptor antagonist (IL-1ra) and soluble receptors to tumor necrosis factor (sTNF-R) in the same setting of the previous report. METHODS Hydrocortisone succinate was infused into healthy volunteers. LPS was then injected immediately or was delayed by 6, 12, or 144 hours (C, C-6, C-12, and C-144, respectively). Subjects receiving LPS alone served as controls. Plasma was analyzed to determine levels of TNF, sTNF-R and IL-1ra by enzyme-linked immunosorbent assay before administration of LPS and at 30-minute intervals after administration of LPS for 6 hours. RESULTS Levels of sTNF-R increased after LPS administration in all groups (p < 0.05 versus baseline) with a significantly higher level recorded in the subjects having received hydrocortisone 144 hours before (C-144, p < 0.05 versus all other groups). TNF levels remained undetectable in association with immediate infusion of LPS (C) and the relatively short delay group (C6). This cytokine peaked 90 minutes after LPS in all other groups, with a significantly higher peak in the C-144 subjects when compared with controls. IL-1ra levels rose in all groups but to a lesser extent in the C group (p < 0.05). CONCLUSIONS These data confirm that glucocorticoids influence the production of both sTNF-R and IL-1ra. The potential for an exaggerated response of sTNF-R exists for an extended period of time after exposure to glucocorticoids.

Restoration of Growth Phenotypes of Escherichia coli DH5α in Minimal Media through Reversal of a Point Mutation in purB

ABSTRACT A point mutation (E115K) resulting in slower growth of Escherichiacoli DH5α and XL1-Blue in minimal media was identified in the purB gene, coding for adenylosuccinate lyase (ASL), through complementation with an E. coli K-12 genomic library and serial subcultures. Chromosomal modification reversing the mutation to the wild type restored growth phenotypes in minimal media.

Polarization, Immigration, Education: What’s Behind the Dramatic Decline in Youth Employment?

Since the beginning of the recent recession, the employment-population ratio for high-school age youth (16-17 years old) has fallen by nearly a third, to its lowest level ever. However, this recession has exacerbated a longer-run downward trend that actually began in the 1990s and accelerated in the early 2000s. There is little research regarding why teen employment has fallen. Some earlier work emphasized labor supply explanations related to schooling and education, such as an increased emphasis on college preparation (Aaronson, Park, and Sullivan 2006), while others have argued that adult immigrants have crowded out teens, at least in part because adult immigrants and native teens tend to be employed in similar occupations (Sum, Garrington, and Khatiwada 2006, Camarota and Jensenius 2010, Smith 2012). This paper presents updated trends in teen employment and participation across multiple demographic characteristics, and argues that, in addition to immigration, occupational polarization in the U.S. adult labor market has resulted in increased competition for jobs that teens traditionally hold. Testing various supply and demand explanations for the decline since the mid-1980s, I find that demand factors can explain at least half of the decline unexplained by the business cycle, and that supply factors can explain much of the remaining decline.

Predicting Exploitation of Disclosed Software Vulnerabilities Using Open-source Data

Each year, thousands of software vulnerabilities are discovered and reported to the public. Unpatched known vulnerabilities are a significant security risk. It is imperative that software vendors quickly provide patches once vulnerabilities are known and users quickly install those patches as soon as they are available. However, most vulnerabilities are never actually exploited. Since writing, testing, and installing software patches can involve considerable resources, it would be desirable to prioritize the remediation of vulnerabilities that are likely to be exploited. Several published research studies have reported moderate success in applying machine learning techniques to the task of predicting whether a vulnerability will be exploited. These approaches typically use features derived from vulnerability databases (such as the summary text describing the vulnerability) or social media posts that mention the vulnerability by name. However, these prior studies share multiple methodological shortcomings that inflate predictive power of these approaches. We replicate key portions of the prior work, compare their approaches, and show how selection of training and test data critically affect the estimated performance of predictive models. The results of this study point to important methodological considerations that should be taken into account so that results reflect real-world utility.