Interblock information in multidimensional block designs

In many experimental situations, d-way heterogeneity among experimental units may be controlled through use of multiple blocking criteria. In some cases it is reasonable to regard some or all of the block effects as random. Then the model is mixed and observations within blocks are correlated. Very general estimators of treatment effects and their dispersion matrix with recovery of interblock information are provided. They apply to designs with d > 1 blocking criteria that may be crossed, nested, or a combination thereof. These general results may be specialized to provide analyses of new classes of MBD's or used directly for numerical analyses of designs in the general class, perhaps through use as the basis for very general computer programs. Estimation of variance components is discussed, and an example is provided to illustrate adaptation of the general results.     

The impact of right-to-work laws on employer unfair labor practice charges

The expected impact of right-to-work (RTW) laws on employer unfair labor practices is discussed within a resource allocation framework. How RTW laws affect the relative prices of different organizing tactics is also considered. Empirical analysis based on cross-sectional data for 1970, 1975, and 1980 shows that the impact of RTW laws on employer unfair labor practice charges is insignificant. Other variables that affect charge activity are also discussed in terms of their effect on employer/union organizing resource allocation decisions.     

Decision-making in extramarital relationships

A model was constructed and used to generate hypotheses regarding situational determinants, motives, and restraints affecting extramarital decision-making. Statistically significant differences between males and females were found on factors influencing extramarital sexual relationships. It was concluded that men have a greater expectation of personal involvement, are strongly influenced by perceived payoffs, and are more likely to respond to what they regard as justifications for their behavior. Women are more responsive to risks which they see as more likely to occur and to be more destructive. Avoiding hurt for themselves and others is an important consideration. Counseling implications are discussed.An earlier version of this article was presented at the national convention of the American Association for Counseling and Development, New York, NY, April, 1985.Ralph A. Meyering is a Professor of Counselor Education at Illinois State University, Elizabeth A. Epling-McWherter is a Executive Director, YWCA, Rock Island, IL 61201. Requests for reprints should be addressed to Dr. Meyering, Department of Specialized Educational Development, Illinois State University, Normal, IL 61761.     

Mathematical Modeling of Reproductive and Developmental Toxic Effects for Quantitative Risk Assessment

A new mathematical dose-response model for reproductive and developmental risk assessment is proposed. The model includes the possibility of an exposure threshold as well as a litter-size effect. Correlation of responses of offspring from the same litter is taken into account through the use of the beta-binomial distribution. Confidence limits for low-dose extrapolation are based on the asymptotic distribution of the likelihood ratio. An empirical comparison of the proposed procedure to that of Rai and Van Ryzin demonstrates the improvement that can be achieved with the new procedure.     

Point Estimates of Cancer Risk at Low Doses

There has been considerable discussion regarding the conservativeness of low-dose cancer risk estimates based upon linear extrapolation from upper confidence limits. Various groups have expressed a need for best (point) estimates of cancer risk in order to improve risk/benefit decisions. Point estimates of carcinogenic potency obtained from maximum likelihood estimates of low-dose slope may be highly unstable, being sensitive both to the choice of the dose–response model and possibly to minimal perturbations of the data. For carcinogens that augment background carcinogenic processes and/or for mutagenic carcinogens, at low doses the tumor incidence versus target tissue dose is expected to be linear. Pharmacokinetic data may be needed to identify and adjust for exposure-dose nonlinearities. Based on the assumption that the dose response is linear over low doses, a stable point estimate for low-dose cancer risk is proposed. Since various models give similar estimates of risk down to levels of 1%, a stable estimate of the low-dose cancer slope is provided by ŝ = 0.01/ED01, where ED01 is the dose corresponding to an excess cancer risk of 1%. Thus, low-dose estimates of cancer risk are obtained by, risk = ŝ × dose. The proposed procedure is similar to one which has been utilized in the past by the Center for Food Safety and Applied Nutrition, Food and Drug Administration. The upper confidence limit, s , corresponding to this point estimate of low-dose slope is similar to the upper limit, q ₁ obtained from the generalized multistage model. The advantage of the proposed procedure is that ŝ provides stable estimates of low-dose carcinogenic potency, which are not unduly influenced by small perturbations of the tumor incidence rates, unlike ₁.     

Risk-Adjusted Mission Value: Trading Off Mission Risk for Mission Value

This article develops a decision-theoretic methodology for the risk-adjusted mission value (RAMV) for selecting between alternative missions in the presence of uncertainty in the outcomes of the missions. This methodology permits trading off mission risk for mission value, something that probabilistic risk analysis cannot do unless it explicitly incorporates both mission value and risk aversion of the project management. The methodology, in its complete implementation, is consistent with the decision theory known as expected utility theory, although it differs from conventional decision theory in that the probabilities and all but one of the utilities are not those of the decision maker. The article also introduces a new interpretation of risk aversion. The methodology is consistent with the elementary management concept concerning division of labor. An example is presented for selecting between discrete alternatives-four landing sites on Mars. A second example is presented for selecting among a set of continuous alternatives-a comet flyby distance. The methodology is developed within the context of scientific missions, but the methodology is equally applicable to any situation requiring outcome value judgments, probability judgments, and risk aversion judgments by different constituencies.