No sustained effect of aerobic or resistance training on insulin sensitivity in nonobese, healthy older women

It is unclear whether long-term aerobic (AT) or resistance (RT) training can improve insulin sensitivity (IS) beyond the residual effect of the last training bout in older women (54-78 years). Therefore, a group of nonobese, healthy older women underwent 6 months of AT (n = 8) or RT (n = 10), and the authors measured IS 4 days after the last training bouts using the hyperinsulinemic-euglycemic clamp technique. Women trained 3 days/week. AT consisted of 25- to 60-min sessions of walking/jogging at 60-95% of maximal heart rate. RT consisted of three sets of nine exercises repeated 10 times at 80% of 1 repetition maximum. AT decreased fat mass, whereas both AT and RT increased fat-free mass. Neither training program, however, improved absolute or relative rates of glucose disposal. The authors therefore concluded that nonobese, healthy older women should perform AT or RT on a daily basis in order to improve IS and maintain the improvement.     

Tree-structured subgroup analysis for censored survival data: Validation of computationally inexpensive model selection criteria

The performance of computationally inexpensive model selection criteria in the context of tree-structured subgroup analysis is investigated. It is shown through simulation that no single model selection criterion exhibits a uniformly superior performance over a wide range of scenarios. Therefore, a two-stage approach for model selection is proposed and shown to perform satisfactorily. Applied example of subgroup analysis is presented. Problems associated with tree-structured subgroup analysis are discussed and practical solutions are suggested.     

Alcohol abuse on a college campus: A needs assessment

This paper reports the results of a needs assessment study conducted by a university-based alcohol abuse prevention project. Data are presented on the drinking patterns and drinking problems of a random sample of 462 students. Results suggest that students are experiencing numerous difficulties in the physical, educational, legal and psychosocial areas due to their use of alcoholic beverages. Implications for prevention and intervention programming are discussed and the need for planning programs from a data-based perspective rather than a rational and intuitive approach is stressed.     

On Order Statistics from Sine Distribution

We derive closed form expressions for the first two moments of order statistics from the sine distribution. For the higher moments, a recurrence relation is given. We also give a recurrence relation for the product moments. These relations will be useful for moment computations based on ordered data.     

Waiting time to exhaust lottery numbers

Questions related to lotteries are usually of interest to the public since people think there is a magic formula which will help them to win lottery draws. This note shows how to compute the expected waiting time to observe specific numbers in a sequence of lottery draws and show that surprising facts are expected to occur.     

Edgeworth Corrections for Realized Volatility

The quality of the asymptotic normality of realized volatility can be poor if sampling does not occur at very high frequencies. In this article we consider an alternative approximation to the finite sample distribution of realized volatility based on Edgeworth expansions. In particular, we show how confidence intervals for integrated volatility can be constructed using these Edgeworth expansions. The Monte Carlo study we conduct shows that the intervals based on the Edgeworth corrections have improved properties relatively to the conventional intervals based on the normal approximation. Contrary to the bootstrap, the Edgeworth approach is an analytical approach that is easily implemented, without requiring any resampling of one's data. A comparison between the bootstrap and the Edgeworth expansion shows that the bootstrap outperforms the Edgeworth corrected intervals. Thus, if we are willing to incur in the additional computational cost involved in computing bootstrap intervals, these are preferred over the Edgeworth intervals. Nevertheless, if we are not willing to incur in this additional cost, our results suggest that Edgeworth corrected intervals should replace the conventional intervals based on the first order normal approximation.     

Multivariate Kendall's tau for change‐point detection in copulas

Statistical procedures for the detection of a change in the dependence structure of a series of multivariate observations are studied in this work. The test statistics that are proposed are $L_1$ , $L_2$ , and $L_{\infty }$ distances computed from vectors of differences of Kendall's tau; two multivariate extensions of Kendall's measure of association are used. Since the distributions of these statistics under the null hypothesis of no change depend on the unknown underlying copula of the vectors, a procedure based on the multiplier central limit theorem is used for the computation of p‐values; the method is shown to be valid both asymptotically and for moderate sample sizes. Alternative versions of the tests that take into account possible breakpoints in the marginal distributions are also investigated. Monte Carlo simulations show that the tests are powerful under many scenarios of change‐point. In addition, two estimators of the time of change are proposed and their efficiency is carefully studied. The methodologies are illustrated on simulated series from the Canadian Regional Climate Model. The Canadian Journal of Statistics 41: 65–82; 2013 © 2012 Statistical Society of Canada     

Do downward private transfers enhance maternal labor supply? Evidence from around Europe

Using data on 2,317 mother–daughter pairs from 10 European countries, we investigate the impact of downward time and monetary transfers on the career choices of transfer-receiving young mothers. For Europe as a whole, we find a strong positive effect of grandchild care on the labor force participation and the degree of labor market involvement of the young mother, but no impact of monetary transfers on either of these decisions. Both recipients and donors with better endowments are more likely to participate in a monetary transaction, while mothers with lower level of human capital are more likely to provide time transfers to their better endowed daughters.     

What motivates adolescent bystanders to intervene when immigrant youth are bullied?

Pathways to bystander responses were examined in both generalized and bias-based bullying incidents involving immigrant-origin victims. Participants were 168 (M_age = 14.54, 57% female) adolescents of immigrant (37.5%) and nonimmigrant backgrounds, who responded to their likelihood of intervening on behalf of either an Arab or Latine victim. Models tested whether contact with immigrants and one's desires for social contact with immigrant-origin peers mediated the effects of individual (shared immigrant background, and discriminatory tendencies) and situational (inclusive peer norms) intergroup factors on active bystander responses. Findings indicated that desires for social contact reliably mediated effects across both victims; however, contact with immigrant peers was only associated with responses to Latine victims. Implications for how to promote bystander intervention are discussed.     

Distribution of product and quotient of bivariate generalized exponential distribution

In this work we derive closed form expressions for the probability density functions and moments of the quotient and product of the components of the bivariate generalized exponential distribution introduced by Kundu and Gupta (J Multivariate Anal, 100:581–593, 2009) and compute the percentage points. The derivations will be useful for practitioners of this bivariate model. We then give a real data application of the product.