Estimation of a non-invertible moving average process: The case of overdifferencing

The effect of differencing all of the variables in a properly specified regression equation is examined. Excessive use of the difference transformation induces a non-invertible moving average (MA) process in the disturbances of the transformed regression. Monte Carlo techniques are used to examine the effects of overdifferencing on the efficiency of regression parameter estimates, inferences based on these estimates, and tests for overdifferenccing based on the estimator of the MA parameter for the disturbances of the differences regression. Overall, the problem of overdifferencing is not serious if careful attention is paid to the properties of the disturbances of regression equations.     

Variables sampling plans for the Poisson and the binomial

Variables sampling plans based upon continuous distributions are well known. The usual assumption is that a measurable characteristic associated with a product has a normal distribution, a case which has been treated extensively in the literature. Other continuous distributions, particularly the exponential, have also been used as models. In this paper we discuss variables sampling plans for situations in which the measurable characteristic has either a Poisson or a binomial distribution.     

Deriving benefits from conflict resolution: A macrojustice assessment

Effective conflict resolution procedures serve to minimize dysfunctional effects of conflict and maximize functional effects. In the literature on conflict resolution procedures, the effectiveness of procedures has been evaluated primarily from the perspective of the individual. This article suggests that a system-level analysis of the pattern of outcomes resulting from different conflict resolution procedures is a necessary component in formulating a comprehensive framework for the design and evaluation of conflict resolution systems in organizations. The analytic questions addressed by this study concern associations between resolution procedures and outcome patterns in a system created specifically for conflict resolution within organizations: the grievance system. The pattern of outcomes was found to vary with the conflict resolution procedure. It is suggested that this has important implications for effective conflict resolution systems.     

Reduced Form Auctions Revisited

This note uses the Theorem of the Alternative to prove new results on the implementability of general, asymmetric auctions, and to provide simpler proofs of known results for symmetric auctions. The tradeoff is that type spaces are taken to be finite.     

A child health production function estimated from longitudinal data. Cebu Study Team

Collaborating researchers used a multi equation model to analyze 3080 mother-infant pairs living on the island of Cebu in the central Philippines and to estimate a child health production function. The econometric methods used eliminated obstacles such as heterogeneity and endogeneity of significant explanatory factors. They also maximized the longitudinal quality of the data. The results showed that morbidity in 1 period reduced infant weight in following periods. For example, diarrhea and febrile respiratory infection reduced growth in the time period following the illnesses. Further effects of some contributing factors were great near birth not diminished with age. For example, breast feeding promoted growth and protected against infection, especially diarrhea and febrile respiratory infection, more substantially near birth than it did later. Further, in urban areas, preventive health care positively affected growth independently of its indirect influence on reducing respiratory infection. Yet it had little effect on diarrhea. Diarrhea had a strong adverse effect on growth. Exposure of the infant to enteric pathogens had the greatest influence on production of diarrhea. In urban areas, exposure included water supply contamination, exposure to feces, a more pathogenic diet, and community crowding. In rural areas, however, exposure included community crowding and increased rainfall which presumably washed feces into the water supply. Household crowding in both urban and rural areas and irritation from smoke in urban areas only tended to bring about febrile respiratory infection.     

Hospitals and material management in the coming decade

The 1990s will be a decade of increasing dramatic and traumatic change for hospitals. Reimbursement, technology, and consumers, either alone or in concert, will be the forces that will shape hospitals in the future. At the end of the 1990s we will have hospitals that offer technology to the critically ill, outpatient surgical services, and comforting care for those in the late years of life. Material management will be important to hospitals because expense control will be as important as ever. However, I believe the role of a material manager will diminish as the services provided change and as the role is folded into the responsibilities of those who manage one of the three critical business areas hospitals will be in. This new hybrid of today's manager will still apply all of the concepts to the distribution of supplies in a hospital as today's material managers do but will use them as only a part of their overall management responsibility.