Subprime outcomes: turmoil in the mortgage market

Until 2007, few Americans had probably heard the word “subprime” - including many homeowners who would come to learn that their own mortgage was a subprime mortgage. Today, subprime mortgages are much discussed because they lie at the center of the turmoil that roiled credit markets in 2007 and 2008.Subprime mortgage

The snail-killing flies of Alaska (Diptera: Sciomyzidae)

Information is given on the geographic distribution, habitat preferences, larval foods, and immature stages for 57 species of 9 genera of Sciomyzidae known to occur in Alaska. An illustrated key to adults is included. Alaska as a habitat for sciomyzid flies is discussed, and information on feeding habits of the larvae is summarized

Tractrices, Bicycle Tire Tracks, Hatchet Planimeters, and a 100-year-old Conjecture

Geometry of the tracks left by a bicycle is closely related with the so-called Prytz planimeter and with linear fractional transformations of the complex plane. We describe these relations, along with the history of the problem, and give a proof of a conjecture made by Menzin in 1906.Comment: 20 pages, 18 figure

U. S. labor supply in the twenty-first century

The American labor force will be transformed as the twenty-first century unfolds, a change that will confront policymakers and business firms with new challenges and new opportunities. The impending slowdown of labor force growth that will accompany the retirement of the baby boom generation already is playing a central role in national debates over the future solvency of Social Security and Medicare, as well as U.S. immigration policies. But labor supply changes will be influenced by other dimensions as well. In the coming decades, American workers are likely to be, on average, older and better educated than today’s labor force. The globalization of labor markets is already opening new employment opportunities for some Americans and changing the wage rates paid to others. The production technologies and personnel policies adopted by tomorrow’s firms will undoubtedly reflect the numbers and types of workers available for employment.Labor supply ; Baby boom generation

Relationship Between Foveal Cone Structure and Visual Acuity Measured With Adaptive Optics Scanning Laser Ophthalmoscopy in Retinal Degeneration.

PurposeTo evaluate foveal function in patients with inherited retinal degenerations (IRD) by measuring visual acuity (VA) after correction of higher-order aberrations.MethodsAdaptive optics scanning laser ophthalmoscopy (AOSLO) was used to image cones in 4 healthy subjects and 15 patients with IRD. The 840-nm scanning laser delivered an "E" optotype to measure AOSLO-mediated VA (AOSLO-VA). Cone spacing was measured at the preferred retinal locus by two independent graders and the percentage of cones below the average density of 47 age-similar healthy subjects was computed. Cone spacing was correlated with best-corrected VA measured with the Early Treatment of Diabetic Retinopathy Study protocol (ETDRS-VA), AOSLO-VA, and foveal sensitivity.ResultsETDRS-VA significantly correlated with AOSLO-VA (ρ = 0.79, 95% confidence interval [CI] 0.5-0.9). Cone spacing correlated with AOSLO-VA (ρ = 0.54, 95% CI 0.02-0.7), and negatively correlated with ETDRS letters read (ρ = -0.64, 95% CI -0.8 to -0.2). AOSLO-VA remained ≥20/20 until cones decreased to 40.2% (CI 31.1-45.5) below normal. Similarly, ETDRS-VA remained ≥20/20 until cones were 42.0% (95% CI 36.5-46.1) below normal. Cone spacing z scores negatively correlated with foveal sensitivity (ρ = -0.79, 95% CI -0.9 to -0.4) and foveal sensitivity was ≥35 dB until cones were 43.1% (95% CI 39.3-46.6) below average.ConclusionsVA and foveal cone spacing were weakly correlated until cones were reduced by 40% to 43% below normal. The relationship suggests that VA is an insensitive measure of foveal cone survival; cone spacing may be a more sensitive measure of cone loss

Labor-market polarization over the business cycle

During the last few decades, labor markets in advanced economies have become "polarized" as relative labor demand grows for high- and low-skill workers while it declines for middle-skill workers. This paper explores how polarization has interacted with the U.S. business cycle since the late 1970s. Consistent with previous work, the authors find that recessions are strongly synchronized across workers with different skills. Even high-skill workers favored by polarization suffer during recessions; this is particularly true during the last two downturns. Additionally, there is no evidence that polarization is driving the recent drop in the job-finding rate that has caused an adverse shift in the Beveridge curve. With this synchronization in mind, the authors then investigate the labor-market transitions of unemployed workers during recessions. When job-finding rates fall in recessions, middle-skill workers appear no more apt to leave the labor force or take low- or high-skill jobs than they are during booms. All in all, the results imply that current distress in the U.S. labor market extends far beyond middle-skill workers, and that recessions in general do not induce reallocation of middle-skill workers to jobs with better long-term outlooks

Testing economic hypotheses with state-level data: A comment on Donohue and Levitt (2001)

State-level data are often used in the empirical research of both macroeconomists and microeconomists. Using data that follows states over time allows economists to hold constant a host of potentially confounding factors that might contaminate an assignment of cause and effect. A good example is a fascinating paper by Donohue and Levitt (2001, henceforth DL), which purports to show that hypothetical individuals resulting from aborted fetuses, had they been born and developed into youths, would have been more likely to commit crimes than youths resulting from fetuses carried to term. We revisit that paper, showing that the actual implementation of DL's statistical test in their paper differed from what was described. (Specifically, controls for state-year effects were left out of their regression model. ) We show that when DL's key test is run as described and augmented with state-level population data, evidence for higher per capita criminal propensities among the youths who would have developed, had they not been aborted as fetuses, vanishes. Two lessons for empirical researchers are, first, that controls may impact results in ways that are hard to predict, and second, that these controls are probably not powerful enough to compensate for the omission of a key variable in the regression model. (Data and programs to support this comment are available on the web site of the Federal Reserve Bank of Boston.

Labor market polarization over the business cycle

One of the most important long-run trends in the U.S. labor market is polarization, defined as the relative growth of employment in high-skill jobs (such as management and technical positions) and low-skill jobs (such as food-service and janitorial work) amid the concurrent decline in middle-skill jobs (such as clerical, construction, manufacturing, and retail occupations). Middle-skill job losses typically result from outsourcing labor to lower-wage countries or from substituting automated technologies for routine tasks. Economists are now beginning to study how long-run polarization might be related to short-run business cycles, but doing so requires the construction of quarterly datasets with consistent occupational data over long periods of time. The authors of this paper construct a new dataset of occupational employment and unemployment that extends from 1947:Q3 to 2013:Q4. Using this dataset, along with more-recent individual-level data from the Current Population Survey, the authors study how recessions typically affect employment in various occupations, what employment alternatives are available to middle-skill workers who become unemployed, and whether the ongoing erosion of middle-skill job opportunities is related to long-term declines in labor force participation among men