The Causes and Consequences of Distinctively Black Names

In the 1960's, Blacks and Whites chose relatively similar first names for their children. Over a short period of time in the early 1970's, that pattern changed dramatically with most Blacks (particularly those living in racially isolated neighborhoods) adopting increasingly distinctive names, but a subset of Blacks actually moving toward more assimilating names. The patterns in the data appear most consistent with a model in which the rise of the Black Power movement influenced how Blacks perceived their identities. Among Blacks born in the last two decades, names provide a strong signal of socio-economic status, which was not previously the case. We find, however, no negative causal impact of having a distinctively Black name on life outcomes. Although that result is seemingly in conflict with previous audit studies involving resumes, we argue that the two sets of findings can be reconciled.

Testing for Racial Differences in the Mental Ability of Young Children

On tests of intelligence, Blacks systematically score worse than Whites, whereas Asians frequently outperform Whites. Some have argued that genetic differences across races account for the gap. Using a newly available nationally representative data set that includes a test of mental function for children aged eight to twelve months, we find only minor racial differences in test outcomes (0.06 standard deviation units in the raw data) between Blacks and Whites that disappear with the inclusion of a limited set of controls. The only statistically significant racial difference is that Asian children score slightly worse than those of other races. To the extent that there are any genetically-driven racial differences in intelligence, these gaps must either emerge after the age of one, or operate along dimensions not captured by this early test of mental cognition.

Neutron Star Kicks from Asymmetric Collapse

Many neutron stars are observed to be moving with spatial velocities, in excess of 500km/s. A number of mechanisms have been proposed to give neutron stars these high velocities. One of the leading classes of models proposed invokes asymmetries in the core of a massive star just prior to collapse. These asymmetries grow during the collapse, causing the resultant supernova to also be asymmetric. As the ejecta is launched, it pushes off (or ``kicks'') the newly formed neutron star. This paper presents the first 3-dimensional supernova simulations of this process. The ejecta is not the only matter that kicks the newly-formed neutron star. Neutrinos also carry away momentum and the asymmetric collapse leads also to asymmetries in the neutrinos. However, the neutrino asymmetries tend to damp out the neutron star motions and even the most extreme asymmetric collapses presented here do not produce final neutron star velocities above 200km/s.Comment: 7 pages, 4 figures, see http://qso.lanl.gov/~clf/papers/kick.ps.gz for full figure

Formation Rates of Black Hole Accretion Disk Gamma-Ray Bursts

While many models have been proposed for GRBs, those currently favored are all based upon the formation of and/or rapid accretion into stellar mass black holes. We present population synthesis calculations of these models using a Monte Carlo approach in which the many uncertain parameters intrinsic to such calculations are varied. We estimate the event rate for each class of model as well as the propagation distance for those having significant delay between formation and burst production, i.e., double neutron star (DNS) mergers and black hole-neutron star (BH/NS) mergers. For reasonable assumptions regarding the many uncertainties in population synthesis, we calculate a daily event rate in the universe for i) merging neutron stars: ~100/day; ii) neutron-star black hole mergers: ~450/day; iii) collapsars: ~10,000/day; iv) helium star black hole mergers: ~1000/day; and v) white dwarf black hole mergers: ~20/day. The range of uncertainty in these numbers however, is very large, typically two to three orders of magnitude. These rates must additionally be multiplied by any relevant beaming factor and sampling fraction (if the entire universal set of models is not being observed). Depending upon the mass of the host galaxy, half of the DNS and BH/NS mergers will happen within 60kpc (for a Milky-Way massed galaxy) to 5Mpc (for a galaxy with negligible mass) from the galactic center. Because of the delay time, neutron star and black hole mergers will happen at a redshift 0.5 to 0.8 times that of the other classes of models. Information is still lacking regarding the hosts of short hard bursts, but we suggest that they are due to DNS and BH/NS mergers and thus will ultimately be determined to lie outside of galaxies and at a closer mean distance than long complex bursts (which we attribute to collapsars).Comment: 57 pages total, 23 figures, submitted by Ap

Hatred and Profits: Getting Under the Hood of the Ku Klux Klan

The Ku Klux Klan reached its heyday in the mid-1920s, claiming millions of members. In this paper, we analyze the 1920s Klan, those who joined it, and the social and political impact that it had. We utilize a wide range of newly discovered data sources including information from Klan membership roles, applications, robe-order forms, an internal audit of the Klan by Ernst and Ernst, and a census that the Klan conducted after an internal scandal. Combining these sources with data from the 1920 and 1930 U.S. Censuses, we find that individuals who joined the Klan were better educated and more likely to hold professional jobs than the typical American. Surprisingly, we find few tangible social or political impacts of the Klan. There is little evidence that the Klan had an effect on black or foreign born residential mobility, or on lynching patterns. Historians have argued that the Klan was successful in getting candidates they favored elected. Statistical analysis, however, suggests that any direct impact of the Klan was likely to be small. Furthermore, those who were elected had little discernible effect on legislation passed. Rather than a terrorist organization, the 1920s Klan is best described as a social organization built through a wildly successful pyramid scheme fueled by an army of highly-incentivized sales agents selling hatred, religious intolerance, and fraternity in a time and place where there was tremendous demand.

Understanding the Black-White Test Score Gap in the First Two Years of School

In previous research, a substantial gap in test scores between White and Black students persists, even after controlling for a wide range of observable characteristics. Using a newly available data set (Early Childhood Longitudinal Study), we demonstrate that in stark contrast to earlier studies, the Black-White test score gap among incoming kindergartners disappears when we control for a small number of covariates. Over the first two years of school, however, Blacks lose substantial ground relative to other races. There is suggestive evidence that differences in school quality may be an important part of the explanation. None of the other hypotheses we test to explain why Blacks are losing ground receive any empirical backing. The difference between our findings and previous research is consistent with real gains made by recent cohorts of Blacks, although other explanations are also possible.

The New Frontier in Risk Assessment: Estimation of Corporate Credit Rating Quality in Emerging Markets

The expansion of credit rating agencies into emerging markets is examined with respect to the overall quality of informational signals provided by ratings to capital markets. Corporate ratings from six developing economies with relatively sophisticated financial sectors are modeled using ordered probit estimation techniques. The paper finds that the informational content in emergingmarket corporate credit ratings is poor ipso facto and compared to similar models of developed market ratings, and suggests that the sample countries are subject to what is termed an ‘emerging market premium’. The consequences of this hypothesis for applications in development finance and regulatory regimes are briefly considered. Procyclicality is not found to be a problem, but this is attributed to clustering rather than through-the-cycle design. It is concluded that corporate credit ratings currently do not actively enhance efficient financial intermediation in developing financial markets and are not a sufficient criterion for risk allocation in regulatory regimes. Keywords: Corporate Credit Rating, Ordered Probit, Financial Intermediatio