J.S. Butler

The importance of employer accommodation on the job duration of workers with disabilities: A hazard model approach

Abstract In line with policies long in place in Western Europe, United States disability policy is now attempting to intervene directly in the labor market to increase the employment of people with disabilities. Beginning in July 1992, the Americans with Disabilities Act of 1990 requires employers to provide reasonable accommodation to workers with disabilities. Here we use a continuous time hazard model on retrospective data from the 1978 Social Security Survey of Disability and Work to estimate the effect of employer accommodation on the subsequent job tenure of workers who suffer a work limiting health impairment. We show that the risk of leaving ones employer is significantly influenced both by accommodation and by the Social Security Disability Insurance replacement rate. Accommodation appears to be as important as a workers expected replacement rate in influencing his risk of job exit.

Revenue Structure and Nonprofit Borrowing

The capital structure of nonprofit organizations plays a crucial role in their sustainability and development. This article explores the extent to which revenue diversification is incorporated into the leverage decision. In addition, this study investigates whether government grants have an impact on the long-term liabilities of nonprofit organizations. A model of nonprofit borrowing is proposed and examined with a national sample of arts, culture, and humanities nonprofit organizations. Model estimates show that nonprofit organizations with higher degree of revenue diversification are more likely to issue debt, but do not necessarily have higher debt ratios. Arts organizations with more government financial support are also more likely to issue debt and to have higher leverage ratios.

Unbiased estimation of the Black/Scholes formula

Abstract The Black/Scholes model gives the price of an option as a function of the true variance rate of the underlying stock and other parameters. Because the true variance rate is unobservable, an estimate of the variance rate is used in empirical tests. But, because the Black/Scholes formula is non-linear in the variance, option price estimates using an estimated variance are biased, even if the variance estimate itself is unbiased. This paper develops an unbiased estimator of the Black/Scholes formula from a Taylor series expansion of the formula and the properties of the pdf of the estimated variance.

Arthritis and the earnings of men. An analysis incorporating selection bias.

Arthritis is a chronic and crippling disease which affects the work effort and earnings of more than 14 million working-age victims. This paper examines the effects of arthritis on the earnings of men aged 18 to 64. Arthritis has large and significant effects on earnings. Most models incorporating selection bias have examined groups with lower labor force participation rates than prime-age males, but significant selection bias is found here. When selection bias is considered, the estimated absolute effects of arthritis are increased and the percentage of the gap between arthritic and non arthritic males explained by arthritis, as opposed to other factors, increases. This study is unusual in identifying the effects of a single disease on earnings.

Generalized instrumental variables estimation of autoregressive conditional heteroskedastic models

Abstract This paper considers an alternative to maximum likelihood (ML) estimation of the autoregressive conditional heteroskedastic (ARCH) model introduced in Engle (1982). Specifically, the analysis demonstrates that Hansens (1982) generalized method of moments (GMM) procedure can be applied for estimation of ARCH models. As an illustration, we compare the results from ML estimation and GMM estimation of Engle and Krafts (1983) ARCH model of U.S. inflation.

Levels and Long-Term Trends in Earnings Inequality: Overcoming Current Population Survey Censoring Problems Using the GB2 Distribution

Over its history, the March Current Population Survey (CPS) has increasingly captured the upper tail of the distribution of all sources of income. This, together with time-consistency problems in top coding, means that users of both the public-use and restricted-access CPS will understate the level of wage earnings and income inequality in earlier years and overstate their growth over time. We address this problem by modeling the personal earnings of full-time, full-year workers using the generalized beta distribution of the second kind, calculating Gini coefficients from the estimated parameters, and comparing them with past findings.

Efficiency results of MLE and GMM estimation with sampling weights

This paper examines GMM and ML estimation of econometric models and the theory of Hausman tests with sampling weights. Weighted conditional GMM can be more efficient than weighted conditional MLE, an inefficient alternative to full information MLE under choice-based sampling, unless regressions have homoscedastic additive disturbances or sampling weights are independent of exogenous variables. GMM variances are necessarily smaller without sampling weights if GMM is the same as MLE or disturbances are homoscedastic, but not in general. Taking into account the dependence of sampling weights on parameters improves the efficiency of estimation.

Tests of the Specification of Univariate and Bivariate Ordered Probit

This note presents tests of the specification of univariate and bivariate ordered probit. The test is sensitive to deviations from either normality or the exogeneity of the explanatory variables. As an example, the ownership of dogs and televisions, both sources of time-intensive entertainment, is studied. The specification for dogs is not rejected, the specification for televisions is rejected at the 2.0 level, and the specification of both together is rejected at the 1.3 level.

Estimating the Correlation in Censored Probit Models

The estimation of censored probit models can result in an estimated correlation between the disturbances approaching [plus]1.0 or -1.0 when most of the observations are selected into the sample and the outcomes are unequally distributed. Outcomes of 0 can induce an estimated correlation of -1.0, and outcomes of 1 can induce an estimated correlation of [plus]1.0. This paper analyzes the population problem, derives corresponding sample conditions, proposes a solution to the problem, and offers a computer program. Copyright 1996 by MIT Press.

Characterization of Community-Acquired Staphylococcus Aureus Infections in Children

Background: Limited data exist concerning characteristics of community-acquired Staphylococcus aureus infections (CA-SAI) in central and eastern Kentucky. Objective: To describe the incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections from January 1, 2004 through December 31, 2005, compare the number of CA-MRSA infections between years, and contrast treatment interventions and antibiotic susceptibility patterns of CA-SAI. Methods: A concurrent and retrospective study was conducted in 125 patients less than 18 years of age with CA-SAI admitted to the hospital/clinic based on criteria from the Centers for Disease Control and Prevention. Data on demographics, length of stay, antibiotic therapy, and antibiotic susceptibilities were collected. Results: Seventy patients were included for analysis (CA-MRSA, n = 51; community-acquired methicillin-susceptible S. aureus [CA-MSSA], n = 19). No statistically significant differences were noted between the number of CA-MRSA infections and the total CA-SAI (9/15 in 2004 vs 42/55 in 2005; p = 0.15). Approximately 75% of patients with CA-SAI were admitted to the hospital with no significant difference in length of stay. Ninety percent of CA-SAI were skin and soft tissue infections. There was a significant difference between groups with cutaneous abscesses (CA-MRSA, n = 37 vs CA-MSSA, n = 6; p = 0.002). Greater than 95% of all isolates were susceptible to vancomycin and trimethoprim/sulfamethoxazole. Half of CA-MRSA patients received inappropriate antibiotic therapy with β-lactam antibiotics or clindamycin without confirmatory disk diffusion test. Twenty-five (49%) patients with CA-MRSA received surgical debridement (S/D) and/or incision and drainage (I/D) with concomitant antibiotic therapy. Four patients with CA-MRSA were rehospitalized for subsequent infections; all 4 received appropriate antibiotic therapy. Conclusions: A noticeable increase in CA-MRSA infections with cutaneous abscess between 2004 and 2005 was noted. In patients receiving inappropriate antibiotic therapy, treatment success was attributed to concomitant S/D and I/D. Further analysis should focus on the impact of antibiotic therapy alone or in combination with S/D and I/D on the incidence of subsequent CA-MRSA infections.