Models for two-way contingency tables

We derive a theoretical and parametrized form for a two-way contingency table by using matrix calculus and Kronecker products.     

Variance bounds for estimators in autoregressive models with constraints

We consider nonlinear and heteroscedastic autoregressive models whose residuals are martingale increments with conditional distributions that fulfil certain constraints. We treat two classes of constraints: residuals depending on the past through some function of the past observations only, and residuals that are invariant under some finite group of transformations. We determine the efficient influence function for estimators of the autoregressive parameter in such models, calculate variance bounds, discuss information gains, and suggest how to construct efficient estimators. Without constraints, efficient estimators can be given by weighted least squares estimators. With the constraints considered here, efficient estimators are obtained differently, as one-step improvements of some initial estimator, similarly as in autoregressive models with independent increments.     

Are People Aware of Their HIV‐positive Status Responsible for Driving the Epidemic in Sub‐Saharan Africa? The Case of Malawi

Many have alleged that those who are now aware that they are HIV‐positive are driving the epidemic. This article reports the results of a study in Malawi that provides empirical evidence of differences in knowledge, attitudes and behaviour between HIV‐positive people and those unaware of their sero‐status. It comes to three conclusions: HIV‐positive people report better knowledge and attitudes; there is substantially higher safer‐sex practice among those aware of their HIV‐positive status; and the assertion that the epidemic is spread by those aware of their positive sero‐status is unsubstantiated. The overall message is that there is a need to accelerate both HIV testing and positive‐prevention work.     

Managing a Low-Incidence Risk: The Example of Toxic Shock Syndrome

This article demonstrates a methodology that allows individuals to reach a personal decision on the use of products which carry very small risks to health and life but also offer considerable benefits. A combination of the principles of dominance, extended dominance, and various methods of direct risk-benefit tradeoffs are shown to reduce the number of possible decisions regarding product use to the one optimal for the value structure of a particular individual. An historical examination of toxic-shock syndrome identifies tampons as a product with risks too small to warrant public intervention but too sizeable to be ignored. The methodology described here can be applied for all such products.     

以学校体育为依托推动全民健身的发展

采用文献综述的方法,论述了学校体育与全民健身的相互关系.并由此提出,学校体育是全民健身活动的基础,加强学校体育的改革与发展、促进学校体育的建设,是实现学校体育向社会化发展的有效途径.     

Assessing performance in local government

The author outlines the complexity of trying to measure performance in local government and poses the questions: performance review by whom?—elected members, professional officers, outside bodies and management consultants: for whom?—ratepayers, recipients of services, central government: and for what purpose?—to cut costs, to cut services, to improve efficiency. He then outlines the various techniques used to measure and assess performance in local government.     

Assertive training for low-income black parents

An assertive training program for parents is described, which was implemented in the Detroit Public Schools Region 7 by therapists from the Wayne State University Psychology Clinic. Fifty-nine parents of preschool age children were trained for 5 consecutive weeks and at one follow-up session. The major goals of the program were to increase the self-esteem of family members and to promote a happier atmosphere in the home. Parents were enthusiastic about this approach and stated that the discussions helped them feel more confident and therefore they were able to handle specific problems with their children more effectively.This project was supported, in part, by a grant from the McGregor, Fund and the Eloise and Richard Webber Foundation.