A FRAMEWORK FOR THE SYSTEM DESIGN PROCESS1

Much discussion and writing about “systems” is often superficial, glib, and of a non-operational nature. This paper presents a cohesive framework for the process of system design which is felt to be of operational value in the design and management of systems. The framework's central tenet is that all systems are made up of entities and the relationships among the attributes of those entities; and that in designing systems, two processes are used, inclusion and structuring. Inclusion is concerned with what entities to include in a system and structuring with how their attributes are to be related. The system design process is directed or driven by a set (system) of criteria. Systems must be viewed with a time dimension: evolution will and should take place, both in the systems themselves and, more importantly, in the criteria that drive the design and evolution of those systems. In this framework, all problem solvers can usefully regard themselves as system designers. Presentation of the framework is followed by examples, discussion of the criteria set, system design tools, and some implications for teachers and practitioners.     

The Additive Risk Model for Estimation of Effect of Haplotype Match in BMT Studies

Abstract. In this article we consider a problem from bone marrow transplant (BMT) studies where there is interest on assessing the effect of haplotype match for donor and patient on the overall survival. The BMT study we consider is based on donors and patients that are genotype matched, and this therefore leads to a missing data problem. We show how Aalen's additive risk model can be applied in this setting with the benefit that the time‐varying haplomatch effect can be easily studied. This problem has not been considered before, and the standard approach where one would use the expected‐maximization (EM) algorithm cannot be applied for this model because the likelihood is hard to evaluate without additional assumptions. We suggest an approach based on multivariate estimating equations that are solved using a recursive structure. This approach leads to an estimator where the large sample properties can be developed using product‐integration theory. Small sample properties are investigated using simulations in a setting that mimics the motivating haplomatch problem.     

Simulating alternative organizational structures of production systems

Changes in international competition lead to changes of the requirements on production enterprises. The introduction of new production technologies does not seem to be exclusively an adequate reaction to the increasing problems. Therefore tools of computer-integrated production (CIM) and new organizational concepts have to be conceived. Because these organizational and technical means are linked on the one hand with severe changes in the production system and, on the other hand, with rather higher economic risks in their realization, the effects have to be estimated in advance in the planning stage. Consideration of dynamical system behaviour plays an important part because the main goal is the improvement of order processing. This paper presents a simulation program, which can be used during the design phase of the organizational structure of production systems as a powerful tool for predicting the effects of new computer-aided tools and structures.     

A multivariate analysis of homogamy in Montevideo,Uruguay

This paper develops multivariate models to describe homogamy or, more generally, marriage preferences, for corresponding characteristics of brides and grooms. The purpose of these models is to obtain interpretable measures of the degree of homogamy (or marriage preference) on one dimension and to adjust these measures for homogamy on other dimensions. The models are applied to a sample of marriages in Montevideo, Uruguay, with pairs of corresponding variables for the brides and grooms. The analysis estimates the unadjusted and adjusted levels of homogamy on previous marital status, age, education, religion, and location. Homogamy on location, or propinquity, is the single most important variable. Previous marital status and age describe the readiness or eligibility to marry and are associated in their effect on homogamy. Education and religion describe vertical and horizontal differentiation of marriage partners, respectively. The multivariate analysis verifies that these dimensions are largely independent of each other.     

A heterarchical generic discrete manufacturing simulation model and its application in a world class manufacturing environment

Current factory design and evaluation is very primitive. Factory components are designed in many cases independently. Product and process design are not well integrated. An encompassing framework is needed for iterating through a series of total factory designs, searching for optimal performance. In addition, a vehicle is needed for predicting the performance of a proposed advanced manufacturing system, so that engineers may have a sound means for evaluating such proposals. A heterarchical discrete manufacturing SIMNET II simulation model (SIMCELLS) was developed as a comprehensive methodology for designing and evaluating discrete manufacturing systems. SIMCELLS allows manufacturing systems engineers to experiment with alternative system structures and control strategies while seeking that combination of design features that will produce the desired overall system performance. The model in combination with a modernization programme is enabling a firm to successfully manufacture and sell trucks meeting international standards. The SIMNET II model     

THE ROLE OF THE MEDIAN LEGISLATOR IN U.S. TRADE POLICY: A HISTORICAL ANALYSIS

In this historical analysis of U.S. trade policy, we apply the median voter model to explain legislative decision making. In this model, the level of tariff protection is expected to change with changes in the median legislator. We show that this simple model does a remarkable job if explaining trade policy until the mid-1930s, when it breaks down. We offer several possible explanations for the breakdown of this model, focusing particularly on the impact of domestic and international institutional changes that may have altered the role of the median legislator in trade policy formation.     

COHORT AND PREJUDICE: WHITES' ATTITUDES TOWARD BLACKS, HISPANICS, JEWS, AND ASIANS

Recent cohorts have been shown to be less prejudiced than theirelders, at least toward blacks. This study addresses two questions:Has this tendency continued among most-recent cohorts of adults?and Does it extend to prejudice toward other ethnic minorities?Using data from a national sample, I focus on stereotype andsocial distance attitudes pertaining to blacks, Hispanics, Asians,and Jews. In general, results indicate that cohorts born alterWorld War II tend to be less prejudiced than prewar cohortstoward each of the four minorities. But most-recent cohortsof Americans show no tendency to be less prejudiced than theirimmediate predecessors born since World War II, and most-recentcohorts residing outside of the South actually tend to be moreprejudiced than their elders.