Sharpening Jensen's Inequality

This article proposes a new sharpened version of Jensen's inequality. The proposed new bound is simple and insightful, is broadly applicable by imposing minimum assumptions, and provides fairly accurate results in spite of its simple form. Applications to the moment generating function, power mean inequalities, and Rao-Blackwell estimation are presented. This presentation can be incorporated in any calculus-based statistical course.     

Job Durations With Worker- and Firm-Specific Effects: MCMC Estimation With Longitudinal Employer–Employee Data

We study job durations using a multivariate hazard model allowing for worker-specific and firm-specific unobserved determinants. The latter are captured by unobserved heterogeneity terms or random effects, one at the firm level and another at the worker level. This enables us to decompose the variation in job durations into the relative contribution of the worker and the firm. We also allow the unobserved terms to be correlated in a model that is primarily relevant for markets with small firms. For the empirical analysis, we use a Portuguese longitudinal matched employer–employee dataset. The model is estimated with a Bayesian Markov chain Monte Carlo (MCMC) estimation method. The results imply that unobserved firm characteristics explain almost 40% of the systematic variation in log job durations. In addition, we find a positive correlation between unobserved worker and firm characteristics.     

Participatory ergonomics: determining injury control "buy-in" of US Army cadre

Overuse injuries account for the majority of lost duty time profiles for soldiers attending Advanced Individual Training (AIT) to become a Combat Medic at Ft. Sam Houston (63% for men and 74% for women). An intervention program was initiated with two AIT Battalions (BN) in an effort to reduce overuse injuries. The purpose of this paper is to describe methods of tracking the participation of supervisors during the intervention program. Methods used to monitor participation included recording the number of coordinating meetings, keeping minutes of advisory committee meetings, and conducting perception surveys. Over an 18-month period, the number of coordinating meetings decreased. Surveys identified the opinions, values, and self-identified roles of supervisors (drill sergeants and cadre) in regard to injury prevention with their assigned student-soldiers before and after an intervention program. At the initiation of the injury control program, 103 individuals completed a 27 question, anonymous survey to assist planners with developing a strategy that would encourage participation of cadre and drill sergeants in preventing injuries. One year later, 191 individuals from the same battalion completed the same survey. Results revealed a slight, statistically insignificant, decrease in supervisors' perception of the presence of overuse injuries in their BN (31.4% vs. 27.4%, p>0.05), and the level of acceptable injuries moved from the 16-30% range to the 1-10% range (chi2=4.65, p<0.05). Post-intervention, more supervisors believed their physical training programs could impact overuse injuries (pre 20.4% vs. post 31.6%, Chi2=6.7, p<0.01). The results reveal several methods to track the involvement of participants, to develop intervention strategies, and to monitor cultural shifts necessary to the injury control process.     

Government policy and its impact on the motor industry

Frequent changes are potentially damaging to companies in sectors where there are long investment lead times and which are unable to respond quickly to changes in government policy. This paper demonstrates the risks which governments run by not providing a consistent, considered policy framework which would allow companies to plan their strategies with a reasonable degree of certainty.     

Effectiveness of a screening tool to detect injuries during Army Health Care Specialist training

The purpose of this project was to evaluate the effectiveness of an initial screening and referral process in reducing the impact of musculosketetal injuries among soldiers attending Health Care Specialist training. Musculoskeletal injury among Army Health Care Specialist students have been reported to be approximately 24% for men and 24-30% for women. The highest student visit rate to the troop medical clinic for musculoskeletal injuries, for men and women, occurs during the first week of training. Anecdotal reports indicate that many students arrive for training with existing injuries or symptoms. This project was designed to assess whether formalized early screening, referral, and intervention could 1) identify arriving students who need musculoskeletal injury-related medical attention, 2) reduce the number of students receiving limited duty status during their 10-week training, 3) decrease the total number of limited duty days for students, and 4) decrease the number of students who cannot graduate due to musculoskeletal injury. Students (N=291) from one company were divided into three groups of 97 students. Three methods were used to screen and refer students for medical intervention: 1) traditional (T), 2) by health care providers (HCP), or 3) by Drill Sergeants (DS). Screening by HCP and DSs involved using a new screening tool to identify and consequently refer students with symptoms to a troop medical clinic (TMC) for early evaluation and intervention. Using the screening tool, HCPs identified 92% of students with injuries, while DSs accurately identified 80%. The screening did not reduce the number of students receiving limited duty status, total limited duty days, or the number of students that could not graduate due to musculoskeletal injury ("holdovers") (p>0.05). The screening tool demonstrated good sensitivity and specificity whether conducted by HCPs or DSs. It failed to demonstrate efficacy in reducing the impact of musculoskeletal injuries among Combat Medic soldiers, as measured by limited duty days and holdovers.     

Explaining antigay violence using target congruence: an application of revised routine activities theory

This research examines predictors of antigay violence (physical assault, sexual assault, and property damage) using Finkelhor and Asdigian's (1996) revised routine activities theory, which predicts that target congruence increases victimization risk. Results indicate about half of the sample experienced at least one type of victimization, while 25% experienced two or more types. Physical violence was the most common type of antigay victimization, with property damage and sexual assault occurring less often. Having a higher level of contact with gay/lesbian organizations and being out of the closet or open about sexual orientation increases the risk of both physical assault and property damage. More frequent drinking to intoxication also increases the risk of antigay-motivated physical assault. The sexual assault model was not significant. Implications for future research and prevention are discussed.     

Stepping stones for the unemployed: the effect of temporary jobs on the duration until (regular) work

Transitions from unemployment into temporary work are often succeeded by a transition from temporary into regular work. This paper investigates whether temporary work increases the transition rate to regular work. We use longitudinal survey data of individuals to estimate a multi-state duration model, applying the ‘timing of events’ approach. The data contain multiple spells in labour market states at the individual level. We analyse results using novel graphical representations, which unambiguously show that temporary jobs shorten the unemployment duration, although they do not increase the fraction of unemployed workers having regular work within a few years after entry into unemployment.     

Sexual orientation and self-reported lying

This paper examines empirical links between sexual orientation and self-reported lying using data collected in several waves of Georgia Institute of Technology’s World Wide Web Users Survey. The data include questions about sexual orientation, lying in cyberspace, and a broad range of demographic information. According to the theoretical framework of Gneezy (Am Econ Rev 95: 384–395, 2005) on the economics of deception, individuals conceal or falsify information when the expected benefit of lying exceeds its costs in terms of psychic disutility. If non-heterosexuals expect to benefit more by falsifying information, then this theory predicts higher rates of lying among non-heterosexuals. The data show that gays and lesbians do indeed report lying more often than heterosexuals, both unconditionally in bivariate correlations and after controlling for demographic and geographic differences. These empirical results are consistent with the conclusion that non-heterosexuals expect higher benefits from concealing personal information because of anti-homosexual discrimination.