Selected health behaviors that influence college freshman weight change

OBJECTIVE AND PARTICIPANTS: The authors investigated the effect of physical activity (PA), fruit and vegetable intake, and alcohol use on 6-month weight change in 193 college freshmen (78.8% white, 88.2% women, 94.5% on a meal plan). METHODS: The authors administered a Web-based survey in fall 2002 (baseline) and spring 2003 (follow-up). RESULTS: There was an overall average weight gain of 2.5 lbs (p < .05), although only 57% reported weight gain (M = 7.1 lbs). Fruit and vegetable intake decreased (p = .034), alcohol use increased (p > .05), and PA was unchanged. Weight gain for students with body mass indexes (BMI) > or =25 kg/m2 was nearly twice that of students with BMIs < 25 (p < .05). Students with low-frequency baseline PA were twice as likely to be overweight. Follow-up data showed that students reporting > or = 4 sessions per week (ie, high frequency) of low-intensity PA were twice as likely to have healthy BMIs as students engaging in low- and moderate-frequency PA. CONCLUSIONS: PA interventions should target freshmen with BMIs > or = 25.     

Review Essay: Animal Magnetism

Qualitative Sociology -     

Physical activity and cognitive-health content in top-circulating magazines, 2006-2008

Physical activity may promote cognitive health in older adults. Popular media play an important role in preventive health communication. This study examined articles discussing associations between physical activity and cognitive health in top-circulating magazines targeting older adults. 42,753 pages of magazines published from 2006 to 2008 were reviewed; 26 articles met inclusion criteria. Explanations regarding the link between physical activity and cognitive health were provided in 57.7% of articles. These explanations were generally consistent with empirical evidence; however, few articles included empirical evidence. Physical activity recommendations were presented in 80.8% of articles; a wide range was recommended (90-300 min of physical activity per wk). Socioeconomic status and education level were not mentioned in the text. Results suggest an opportunity for greater coverage regarding the role of physical activity in promoting cognitive health in popular media. Magazine content would benefit from including more empirical evidence, culturally sensitive content, and physical activity recommendations that are consistent with U.S. guidelines.     

THE POTENTIAL FOR BIAS IN PRINCIPAL CAUSAL EFFECT ESTIMATION WHEN TREATMENT RECEIVED DEPENDS ON A KEY COVARIATE

Motivated by a potential-outcomes perspective, the idea of principal stratification has been widely recognized for its relevance in settings susceptible to posttreatment selection bias such as randomized clinical trials where treatment received can differ from treatment assigned. In one such setting, we address subtleties involved in inference for causal effects when using a key covariate to predict membership in latent principal strata. We show that when treatment received can differ from treatment assigned in both study arms, incorporating a stratum-predictive covariate can make estimates of the "complier average causal effect" (CACE) derive from observations in the two treatment arms with different covariate distributions. Adopting a Bayesian perspective and using Markov chain Monte Carlo for computation, we develop posterior checks that characterize the extent to which incorporating the pretreatment covariate endangers estimation of the CACE. We apply the method to analyze a clinical trial comparing two treatments for jaw fractures in which the study protocol allowed surgeons to overrule both possible randomized treatment assignments based on their clinical judgment and the data contained a key covariate (injury severity) predictive of treatment received.     

Gender differences in the ultimatum game

I explore the behavior of men and women in the ultimatum game. In one treatment, players remain mutually anonymous. In the second treatment, players'gender is common knowledge. Average offers made do not differ based on the gender of player 1. Offers are affected by the gender of player 2, with men attracting higher offers, particularly from female players 1. Players 2 of both genders choose a higher minimum acceptable offer when facing a female player 1. These patterns led to substantial differences in earnings. Such striking differences in expectations and decisions could impact salary negotiations and other real-world transactions.