Demographic foundations of the sex role revolution

The current revolution in sex roles is not simply the result of feminist ideology; it is a consequence of the demographic changes that have occurred during this century. Women seek work outside the home in response to a situation created, in part, by the decline in birth and mortality rates. Engaging in productive labor is not, however, a new activity for married women. In fact, the male "breadwinner" system of the last century has been a historical aberration. Women have traditionally participated in production. Feminism clearly provides an ideological basis for the new egalitarianism in marriage, but it is not possible to meaningfully examine the changing sex roles during this century without also examing the concurrent demographic trends.     

Three-stage designs for monitoring clinical trials

Optimal three-stage designs with equal sample sizes at each stage are presented and compared to fixed sample designs, fully sequential designs, designs restricted to use the fixed sample critical value at the final stage, and to modifications of other group sequential designs previously proposed in the literature. Typically, the greatest savings realized with interim analyses are obtained by the first interim look. More than 50% of the savings possible with a fully sequential design can be realized with a simple two-stage design. Three-stage designs can realize as much as 75% of the possible savings. Without much loss in efficiency, the designs can be modified so that the critical value at the final stage equals the usual fixed sample value while maintaining the overall level of significance, alleviating some potential confusion should a final stage be necessary. Some common group sequential designs, modified to allow early acceptance of the null hypothesis, are shown to be nearly optimal in some settings while performing poorly in others. An example is given to illustrate the use of several three-stage plans in the design of clinical trials.     

Asymptotic equivalence of the harrell-davis median estimator and the sample median

This paper presents an asymptotic equivalence result with a sharp rate of convergence forthe sample median and the Harrell-Davis median estimator. The consequences of this result are discussed.