6,741 research outputs found
Enabling Data-Driven Transportation Safety Improvements in Rural Alaska
Safety improvements require funding. A clear need must be demonstrated to secure funding. For transportation safety, data, especially data about past crashes, is the usual method of demonstrating need. However, in rural locations, such data is often not available, or is not in a form amenable to use in funding applications. This research aids rural entities, often federally recognized tribes and small villages acquire data needed for funding applications. Two aspects of work product are the development of a traffic counting application for an iPad or similar device, and a review of the data requirements of the major transportation funding agencies. The traffic-counting app, UAF Traffic, demonstrated its ability to count traffic and turning movements for cars and trucks, as well as ATVs, snow machines, pedestrians, bicycles, and dog sleds. The review of the major agencies demonstrated that all the likely funders would accept qualitative data and Road Safety Audits. However, quantitative data, if it was available, was helpful
ERBE/NOAA-9 observations for the FIRE/SRB Wisconsin experiment region from October 14 through October 31, 1986
Tables are presented which show ERBE/NOAA-9 radiances, resolution size, and pixel location for the FIRE/SRB Wisconsin experiment region from October 1 through October 31, l986. Also presented is an analysis of the ERBE point spread function used to estimate pixel resolution size for the scanner instrument
Comparative Advantage, Learning, and Sectoral Wage Determination
We develop a model in which a worker's skills determine the worker's current wage and sector. Both the market and the worker are initially uncertain about some of the worker's skills. Endogenous wage changes and sector mobility occur as labor-market participants learn about these unobserved skills. We show how the model can be estimated using non-linear instrumental-variables techniques. We then apply our methodology to study the wages and allocation of workers across occupations and across industries. For both occupations and industries, we find that high-wage sectors employ high-skill workers and offer high returns to workers' skills. Estimates of these sectoral wage differences that do not account for sector-specific returns are therefore misleading. We also suggest further applications of our theory and methodology.
Comparative Advantage, Learning, and Sectoral Wage Determination
We develop a model in which a worker's skills determine the worker's current wage and sector. Both the market and the worker are initially uncertain about some of the worker's skills. Endogenous wage changes and sector mobility occur as labor-market participants learn about these unobserved skills. We show how the model can be estimated using non-linear instrumental-variables techniques. We then apply our methodology to study the wages and allocation of workers across occupations and across industries. For both occupations and industries, we find that high-wage sectors employ high-skill workers and offer high returns to workers' skills. Estimates of these sectoral wage differences that do not account for sector-specific returns are therefore misleading. We also suggest further applications of our theory and methodology. Dans cet article, nous cherchons à développer un modèle par lequel le salaire d'un travailleur est fonction de ses qualifications. Le marché ainsi que le travailleur sont au préalable dans l'incertitude quant à certaines de ces qualifications. L'endogénéité à la fois des changements de salaire et des décisions de changements du secteur d'affiliation résulte du processus d'apprentissage relié aux qualifications du travailleur. Nous montrons ensuite comment le modèle peut être estimé par les méthodes des variables instrumentales non-linéaires. Nous appliquons notre méthodologie à l'étude des salaires et de l'allocation des travailleurs aux différentes occupations et industries. Nous trouvons que les secteurs à salaires élevés emploient des travailleurs ayant davantage de qualifications et que ces secteurs rémunèrent ces qualifications à un taux supérieur relativement aux secteurs à faibles salaires. Les estimés des rendements associés aux qualifications qui ne tiennent pas compte du fait que les rendements diffèrent d'un secteur à un autre sont par conséquent erronés. Nous proposons enfin d'autres applications possibles de notre méthodologie.comparative advantage, learning, non-linear instrumental variables, avantages comparés, apprentissage, variables instrumentales
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Layoffs and Lemons
We provide theoretical and empirical analyses of an asymmetric-information model of layoffs. When firms have discretion with respect to whom to lay off, the market infers that laid-off workers are of low ability. Assuming that no such negative inference is warranted if workers are displaced in a plant closing, postdisplacement wages should be lower and postdisplacement unemployment spells should be longer for those displaced by layoffs than for those displaced by plant closings, but predisplacement wages should not differ by cause of displacement. Evidence on displaced workers from Current Population Surveys supports all three of our model's predictions.Economic
Does Unmeasured Ability Explain Inter-Industry Wage Differentials?
This paper provides empirical assessments of the two leading explanations of measured inter-industry wage differentials: (1) true wage differentials exist across industries, and (2) the measured differentials simply reflect unmeasured differences in workers' productive abilities. First, we summarize the existing evidence on the unmeasured-ability explanation, which is based on first-differenced regressions using patched Current Population Survey (CPS) data. We argue that these existing approaches implicitly hypothesize that unmeasured productive ability is equally rewarded in all industries. Second, we construct a simple model in which unmeasured ability in not equally valued in all industries; instead, there is matching. This model illustrates two endogeneity problems inherent in the first-differenced regressions using CPS data: whether a worker changes jobs in endogenous, as is the industry of the new job the worker finds. Third, we propose two new empirical approaches designed to minimize these endogeneity problems. We implement these procedures on a sample that allows us to approximate the experiment of exogenous job loss: a sample of workers displaced by plant closings. We conclude from our findings using this sample that neither of the contending explanations fits the evidence without recourse to awkward modifications, but that a modified version of the true-industry-effects explanation fits more easily than does any existing version of the unmeasured-ability explanation.
Hypnotics' association with mortality or cancer: a matched cohort study
Objectives: An estimated 6%e10 % of US adults took a hypnotic drug for poor sleep in 2010. This study extends previous reports associating hypnotics with excess mortality. Setting: A large integrated health system in the USA. Design: Longitudinal electronic medical records were extracted for a one-to-two matched cohort survival analysis. Subjects: Subjects (mean age 54 years) were 10 529 patients who received hypnotic prescriptions and 23 676 matched controls with no hypnotic prescriptions, followed for an average of 2.5 year
Effect of Artificial Gravity: Central Nervous System Neurochemical Studies
The major objective of this project was to assess chemical and morphological modifications occurring in muscle receptors and the central nervous system of animals subjected to altered gravity (2 x Earth gravity produced by centrifugation and simulated micro gravity produced by hindlimb suspension). The underlying hypothesis for the studies was that afferent (sensory) information sent to the central nervous system by muscle receptors would be changed in conditions of altered gravity and that these changes, in turn, would instigate a process of adaptation involving altered chemical activity of neurons and glial cells of the projection areas of the cerebral cortex that are related to inputs from those muscle receptors (e.g., cells in the limb projection areas). The central objective of this research was to expand understanding of how chronic exposure to altered gravity, through effects on the vestibular system, influences neuromuscular systems that control posture and gait. The project used an approach in which molecular changes in the neuromuscular system were related to the development of effective motor control by characterizing neurochemical changes in sensory and motor systems and relating those changes to motor behavior as animals adapted to altered gravity. Thus, the objective was to identify changes in central and peripheral neuromuscular mechanisms that are associated with the re-establishment of motor control which is disrupted by chronic exposure to altered gravity
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