A brief introduction to marginal analysis for the micro-economics principles course

This brief note provides a simple, yet powerful example of how the marginal cost/marginal benefit principle can be used in everyday life. Using the decision of the optimal choice of speed on the highway, this note was developed for use as one of the first readings in an introductory microeconomics course. It is clear in this demonstration that marginal cost is increasing, while marginal benefit is decreasing, and how the intersection of these two curves shows the optimal choice. In addition, shifts in the curves can easily be demonstrated as an introduction to supply and demand.marginal analysis; economic education

A response to unfounded criticisms of Burkey and Obeng (2004) made by the IIHS (2005)

Abstract: The Insurance Institute for Highway Safety mailed an essay written by Richard Retting and Sergey Kyrychenko (IIHS, 2005) to many universities and individuals where they accused my coauthor and me of being Junk Scientists. This has become a typical pattern for the IIHS, attacking every study that fails to find a benefit of Red Light Cameras, but never criticizing work that supports their beliefs. In this paper I defend my work against their claims, and pose the question: Who are the real junk scientists?Red Light Camera; Intersection Safety;

Crash Risk Reduction at Signalized Intersections Using Longitudinal Data

This study extends the previous work of Burkey and Obeng (2004) that examined the impact of red light cameras on the type and severity of crashes at signalized intersections in Greensboro, NC. The extension takes the following form. First, we extend the data to cover 57 months, and to include demographics, technology variables, the condition of a driver at the time of the crash, vehicle characteristics, land use and visual obstruction. Second, instead of examining the impact of red light cameras, we focus on identifying the determinants of crash severity, two-vehicle crashes, and property damage costs. The major findings are that the safety impacts of seatbelt use outweigh the impacts of airbags deploying because the latter tends to increase evident injuries and property damage costs, while the former reduces these injuries. We also find that head-on collisions and under rides increase evident injuries. For two-vehicle crashes, we find that the risk of severe injuries increases in pickup-pickup crashes and SUV-pickup crashes, while the risk of possible injuries increases in car-truck crashes. For property damage costs, we found the condition of the driver at the time of the crash (i.e., illness, impaired, medical condition, driver falling asleep, driver apparently normal) to be important determinants in increasing these costs. The types of accidents that we found to increase property damage costs are running into a fixed object and under rides. Finally, we found that property damage costs of crashes are low where the land uses are commercial and institutional suggesting that the accidents that occur in these areas are minor.longitudinal data; accidents; intersections

A preliminary investigation of welfare migration induced by time limits

Studies on welfare programs in the United States have identified three types of welfare migration (employment, benefit, and amenity-related). This paper introduces a fourth type of migration induced by welfare time limits. After a welfare-dependent family runs out of benefits, it is possible for them to reset the Temporary Assistance for Needy Families time clock by crossing state lines to extend their benefits. Our theoretical results suggest that the likelihood of migration increases if the migration distance is small or the gain from the move is large. We hypothesize that, ceteris paribus, families migrating in order to extend their benefits will minimize the distance they migrate, and will be likely to move into the nearest state, especially into counties just across the state border. We utilize macro data at the county level to look for evidence of time-limit induced migration. Estimates indicate that time limits may be associated with an increase in welfare migration.welfare reform; migration

Factors affecting the location of payday lending and traditional banking services in North Carolina

Payday lending is a relatively new and fast growing segment of the “fringe banking” industry. This paper offers a comparative, descriptive analysis of the location patterns of traditional banks and payday lenders. Utilizing a dataset at the Zip Code Tabulation Area level in North Carolina, we perform negative binomial regressions and find evidence supporting some, but not all common assertions about the location patterns of both types of institutions. A key finding is that after controlling for many covariates, race is still a powerful predictor of the locations of both banks and payday lenders.payday lending, fringe banking, location analysis

Cosmological parameter estimation from galaxy surveys

Galaxy surveys contain a wealth of information on the distribution of galaxies and dark matter in the Universe. Modern surveys yield large numbers of redshifts giving an unprecedented insight into the clustering of galaxies. The peculiar velocities of galaxies - motions caused by the local gravitational potential - allow the dark matter distribution to be inferred. This thesis deals with the statistical analysis of galaxy redshift and peculiar velocity surveys, concentrating on their exploitation for cosmological parameter estima­tion. The work is divided into two themes. Firstly predictions are made of the information content of galaxy surveys and the problem of optimising surveys’ designs to maximize this information is discussed. The second part is the development of a maximum likelihood method of constraining key parameters which deals most accurately with the spherical nature of modern wide-field surveys. Throughout the thesis, the 6 degree Field Galaxy Survey (6dFGS) is used to demonstrate the methods. Through application of the informa­tion theory to the 6dFGS, key predictions are made as to the strengths of the survey. The likelihood method is also developed with the intention that it be used in a future analysis of the 6dFGS.In the information analysis section, the Fisher information matrix is introduced. It is used to obtain new analytical expressions for the cosmic variance of key cosmological parameters constrained from the galaxy power spectrum of any survey given its volume. A technique for survey optimisation is introduced, which defines a set of parameters to describe the geometry and selection criteria of a galaxy survey. Using reasonable assump­tions about the dependency of a survey’s Limescale on these parameters, it is shown that the survey design may be optimized in the sense of maximizing its information content with respect to a cosmological parameter. The optimal design is calculated for the 6dFGS and predictions are made from the Fisher matrix, of the attainable uncertainties on future cosmological parameter predictions from the survey. Similar analysis is performed for the peculiar velocity survey.To fully exploit the information content of redshifts and velocities it is necessary to perform a joint analysis of the two. This is particularly suitable for the 6dFGS since it incorporates a redshift and velocity survey which use similar selection critetia. The Fisher matrix for the two data sets of redshifts and velocities is derived. It is then used to pre­dict the information content of the combined surveys, as well as the correlations between the parameters. It is found that the great advantage of combining redshifts and peculiar velocities is that the combination breaks the degeneracy between the redshift distortion parameter and the mass-galaxy correlation coefficient - allowing the simultaneous constraint of both.The second part of the work develops a method of constraining these two parameters. Redshift space distortions are best dealt with by expanding the galaxy distribution of a survey in spherical Bessel functions and spherical harmonics. This separation of angular and radial distributions is also convenient analytically as a way of separating out the win­dow function from the radial selection function. Models are constructed of the combined covariance matrix of the redshift—velocity data set. The models accurately describe the ef­fects of redshift space distortions and stochastic galaxy biassing. to linear order. Software developed to perform this analysis is then tested on a suite of simulations of the 6dFGS.Finally attention is paid to the problem of optimal data compression. In a real survey with a complicated survey mask, the final covariance matrix can be unfeasibly large to invert at different points in parameter space. The best way of performing this compression is shown to be Generalised Optimal Mode Analysis (GOMA) which optimally compresses the data set in a way that retains the most information on a specific parameter. The results of the maximum likelihood method applied to a compressed data set from the 6dFGS simulations are shown. The results are a good reflection of what will be possible when the survey reaches completion in mid-2005

Unintended Migration Consequences of US Welfare Reform

Researchers have analyzed whether US welfare reform has induced interstate migration. Empirical results are inconclusive because methodologies are based on pre-reform thinking. This paper presents a post-reform migration model. We find that recipients move to avoid harsh sanction policies, seek lenient work requirements, and extend time limits. Unlike the first two behavioral responses, the latter is controversial. Critics will argue that such moves are illegal, and violators can be prosecuted because states share data. However, only active cases are being shared, meaning violators cannot be caught. Our model produces testable hypotheses which are consistent with (and reconcile) previous empirical results.Migration, Welfare reform

Making Educational and Scholarly Videos with Screen Capture Software

This resource describes several options for making educational videos using “screencasting”, or “screen capture” software. The author (who has over 300 screencasted videos on YouTube and indexed on his website, www.burkeyacademy.com) describes the software and hardware tools needed, including some open source and free-to-use tools. Links to some “how to” videos are included, as well as some links to other example videos demonstrating novel professional uses for screencasting

Protein Sequence-Structure-Function Relationship: Testing KE-50 Modification on Recombinant Green Fluorescent Protein (AcGFP)

Protein modification shows promise for improving the effectiveness of protein therapy, including the use of Interferon-beta-1b for the treatment of multiple sclerosis. The addition of a chain of 50 lysine and glutamic acid residues (also called a KE50 modification) was tested on green fluorescent protein (AcGFP) to determine its effect on the bioactivity of the protein. Standard transformation protocol was used to grow the normal and modified proteins in E.Coli, and the bioactivity of the protein was measured using quantum yield and extinction coefficients to determine the reduction in brightness from the native form to the modified form. The brightness of the modified protein was reduced to 65% of the original brightness, showing that the modification reduces protein bioactivity but does not eliminate it. The same transformation experiment was attempted to grow native and KE50 modified versions of interferon-beta-1b, but the growth of the protein in E.Coli was not successful. If future efforts to create a modified version of interferon-beta-1b are successful, it could prove to be a more successful treatment for multiple sclerosis which has reduced immunogenicity and longer residence time in the blood compared to the current treatment