Cybersex: Outercourse and the Enselfment of the Body

The increased popularity of the Internet invites the possibility of repackaging familiar activities in a new medium. Sex is one such activity—an age‐old topic with a new cybertwist. The new technologies of computer‐mediated communication allow us to examine the nature of human interaction in a uniquely disembodied environment that potentially transforms the nature of self, body, and situation. Sex—fundamentally a bodily activity—provides an ideal situation for examining these kinds of potential transformations. In the disembodied context of on‐line interaction both bodies and selves are fluid symbolic constructs emergent in communication and are defined by sociocultural standards. Situations such as these are suggestive of issues related to contemporary transgressions of the empirical shell of the body, potentially reshaping body‐to‐self‐to‐social‐world relationships.     

Youth unemployment and government policy

Young people of working age tend to be particularly prone to labor market inefficiencies that keep their wages excessively high and their employment excessively low. These inefficiencies are usually magnified through unemployment benefit systems. This paper examines how these problems can be tackled through “employment vouchers,” i.e. hiring subsidies or tax breaks for the unemployed. It examines how vouchers to the young unemployed should differ from those to the adult unemployed. The employment vouchers considered here reduce unemployment and impose no cost on the government, since they are financed by the induced fall in government expenditures on unemployment benefits. Among other things, we find that young workers should receive lower vouchers as displacement of the old rises and as deadweight from providing vouchers to the old increases.     

Partial central subspace and sliced average variance estimation

Sliced average variance estimation is one of many methods for estimating the central subspace. It was shown to be more comprehensive than sliced inverse regression in the sense that it consistently estimates the central subspace under mild conditions while slice inverse regression may estimate only a proper subset of the central subspace. In this paper we extend this method to regressions with qualitative predictors. We also provide tests of dimension and a marginal coordinate hypothesis test. We apply the method to a data set concerning lakes infested by Eurasian Watermilfoil, and compare this new method to the partial inverse regression estimator.     

Testing hypotheses about covariance matrices using bootstrap methods

The usual chi-squared approximation to test statistics based on normal theory for testing covariance structures of multivariate populations is very sensitive to the normality assumption. Two general bootstrap procedures are developed in this paper to obtain approximately valid critical values for these test statistics when the data are not normally distributed. The first is based on separate sampling from individual samples, and the second is based on sampling from pooled samples. Although the second method requires more assumptions, its small sample properties are better.     

A comparison of stein-like procedures for estimating linear regression models with multicollinear data

This paper compares several Stein-like estimation methods for estimating regression parameters. The criterion function was the mean-squared error of prediction and the parameter of interest was the mean of the response variable at the sampled values of the control variables. Large sample simulation techniques were used to evaluate the mean-squared error of the predictions. The parameters of interest were varied systematically over wide ranges.     

A Test for the Equality of Parameters for Separate Regression Models in the Presence of Heteroskedasticity

Testing for the equality of regression coefficients across two regressions is a problem considered by analysts in a variety of fields. If the variances of the errors of the two regressions are not equal, then it is known that the standard large sample F-test used to test the equality of the coefficients is compromised by the fact that its actual size can differ substantially from the stated level of significance in small samples. This article addresses this problem and borrows from the literature on the Behrens-Fisher problem to provide some simple modifications of the large sample test which allows one to better control the probability of committing a Type I error. Empirical evidence is presented which indicates that the suggested modifications provide tests which are superior to well-known alternative tests over a wide range of the parameter space.     

Increasing the sample size at interim for a two‐sample experiment without Type I error inflation

For the case of a one‐sample experiment with known variance σ²=1, it has been shown that at interim analysis the sample size (SS) may be increased by any arbitrary amount provided: (1) The conditional power (CP) at interim is ?50% and (2) there can be no decision to decrease the SS (stop the trial early). In this paper we verify this result for the case of a two‐sample experiment with proportional SS in the treatment groups and an arbitrary common variance. Numerous authors have presented the formula for the CP at interim for a two‐sample test with equal SS in the treatment groups and an arbitrary common variance, for both the one‐ and two‐sided hypothesis tests. In this paper we derive the corresponding formula for the case of unequal, but proportional SS in the treatment groups for both one‐sided superiority and two‐sided hypothesis tests. Finally, we present an SAS macro for doing this calculation and provide a worked out hypothetical example. In discussion we note that this type of trial design trades the ability to stop early (for lack of efficacy) for the elimination of the Type I error penalty. The loss of early stopping requires that such a design employs a data monitoring committee, blinding of the sponsor to the interim calculations, and pre‐planning of how much and under what conditions to increase the SS and that this all be formally written into an interim analysis plan before the start of the study. Copyright © 2009 John Wiley & Sons, Ltd.