ON FUZZY GOAL PROGRAMMING*

This paper illustrates how the goal programming problem with fuzzy goals having linear membership functions may be formulated as a single goal programming problem. Also, a previously defined method for dealing with fuzzy weights for each of the goals is re-examined.     

这液体能替代食物吗

<正>Rob Rhinehart所尝试的自助式调配"液体食品",并长期食用的做法,对于普通人来讲,却属于"危险动作",必须要向读者强调"请勿模仿"。而且,据某松鼠透露,实验室的同事试着尝试了类似的营养液,七天后——差点儿没把自己恶心死。Rob Rhinehart已经尝试将自己的独家配方商品化,并已经募集了超过60万美元...     

The Organizational Niche

Although the concept of niche has been extremely useful in sociological theory and research, some aspects of the concept have not been clearly developed. This article advances a theoretical reconstruction of the concept of niche, with special application to organizations. The proposed formal model unifies several active lines of sociological theory. It also extends the notion of the niche from the realm of behaviors to apply to the rules coding social identities and organizational forms. The reconstruction gives deeper insight into the niche of an organizational population as well as individual organizations. Finally, the model analyzes the (thus far) tacit assumption that niches are convex, examines the implications of convexity for commonly used measures of niche width, and provides a general sociological argument for the predominance of convex niches.     

A NOTE ON ARMA PARAMETERISATION*

This paper considers the relationship between ARMA parameterisations of models for y(t) and Ay(t), where A is invertible and y(t) is a vector time series (t = 0,±1,…). An ARMA model for the transformed series Ay(t) may have fewer parameters than a model for y(t). This paper shows that such a saving is illusory because the apparently saved parameters are exactly balanced by the number of new parameters appearing in A.     

THE CONVERGENCE OF AUTOCORRELATIONS AND AUTOREGRESSIONS1

For a general class of scalar stationary processes, essentially those for which the best linear predictor is the best predictor (in the mean square sense), it is shown that, under fairly minor additional conditions, the sample autocorrelations converge to the true values almost surely and hniformly in the lag, t, at a rate (T^-1log T)^1/2, where T is the sample size. For ARMA processes, if |t|(log T)^a, a < ∞, the rate is the best possible, namely (T^-1log log T)^1/2. In particular the somewhat implausible condition, on the innovations, that E{ε(t)²| F_t-l} is constant is avoided in these results. The theorems are used to discuss autoregressive approximation. When the stationary process is a vector process the condition on the innovation sequence, ε(t), that E{ε(t)ε(t)| F_t-l} be constant, cannot be entirely avoided in relation to autoregressive approximation. This is also discussed.     

Increasing the degrees of freedom in future group randomized trials: the df* approach

This article builds on the previous article by Blitstein et al. (2005), which showed how external estimates of intraclass correlation can be used to improve the precision for the analysis of an existing group randomized trial. The authors extend that work to sample size estimation and power analysis for future group-randomized trials. Often this approach will allow a smaller study than would otherwise be possible without sacrificing statistical power. Such studies are needed, for example, as pilot studies to help plan for a full-scale efficacy trial, as replication studies, or in situations in which resource constraints prohibit a larger trial. The authors discuss the circumstances under which this strategy will be most helpful and the risks associated with conducting smaller studies.     

Local Environmental Groups: A Systematic Enumeration in Two Geographical Areas*

Abstract Local environmental groups, although acknowledged increasingly since the mid‐1980s, have not been sampled systematically, have been reported to consist of only a few types, and are often considered to be of only minor political significance. In this study we systematically inventoried all local environmental groups in two U.S. geographical areas: the Delmarva Peninsula and the state of North Carolina. We found 566 local groups, seven to 20 times the number reported in the best published directory. Three‐quarters did not fit the types most commonly characterized in the literature. Extrapolating from our study areas, we estimate that 16,000 to 30,000 local environmental groups are active in the United States. We find that these groups have a subset of “core” members, those active in organizing and local operations. We estimate the population of core members at 265,000 to 290,000, over 50 times the total of professional staff members of all U.S. national environmental organizations. These groups affect local and state environmental policy, enforcement of environmental laws, the shaping of environmental issues, and the social infrastructure for environmental behaviors.     

Where do organizational forms come from?

Most theory and research on organizations assumes that the great diversity of organizational attributes reflects variation in implementation of a relatively small number of forms. Modern conceptions of organizational form concentrate on discontinuities in distributions of either attributes or relationships with other organizations. We argue that this approach be supplemented with an explicitly dynamic one that focuses on processes that create and erode boundaries in the organizational world. This paper discusses some of the advantages of this approach and specifies a number of processes that create and erode boundaries around organizational populations.