Policy Coalitions in the U.S. Congress: A Spatial Duration Modeling Approach

This paper applies spatial duration models to the analysis of cosponsorship coalitions in the U.S. House of Representatives. This approach provides a unique and simultaneous statistical analysis of ideological space (specifically, coalition formation) and geographical space. Typically, duration models are associated with temporal longitudinal data, but recently have been adapted to the spatial domain (Pellegrini and Reader 1996). In this paper, spatial duration models are further adapted to examine ideological space including a consideration of unobserved sources of spatial variation (or omitted variable bias). We examine two features of cosponsorship coalitions, breadth and clustering. Breadth is defined as the ideological distance between the two most extreme members of the coalition which is an important “signal” to the rest of Congress regarding the scope and broad appeal of the proposed legislation. In contrast, clustering refers to the distance between individual members of a coalition and reveals the tendency, or not, of ideologically similar members of Congress to support various bills. To examine breadth and clustering, we employ spatial duration models of cosponsorship that permit a multivariate analysis incorporating both the characteristics of members of Congress and the geographical regions they represent. Results indicate that cosponsorship coalition patterns are primarily determined by the content of the legislation, not the actions of the coalition leadership. While the leadership characteristics of sponsors have a limited effect on cosponsorship breadth, the size of the coalition is the primary determinent. Leadership characteristics also have little effect on cosponsorship clustering. Rather, clustering is due to members' policy preferences, as measured by distance to the coalition leader. In addition, the duration analysis results suggest that geographical proximity between members of Congress “overcomes” ideological distance. Finally, the spatial duration approach is noted as a fruitful methodology for examining explicitly spatial patterns in both ideological or geographical space.     

Set-determined Process and the Growth of Spatial Structure

We present an analysis of the effects of different information flow patterns on the growth of spatial structure in a broad class of systems. Examples are drawn from plant and message diffusion processes, the growth of herding in animal populations and, in particular, the evolution of cities in human populations. We model the actions of an “individual” as a response to gradients in a transformation of the “real” space, this transformation being the individual's information map of the space. Interesting deductions occur as a result of allowing the individual's information map to vary from extremely local to extremely global. In the city growth model for example, if migration decisions are based upon extremely local information, then the system is characterized by instability and the lack of any well-defined spatial structure. As the localness of this information map decreases, the system is characterized by the development of well defined spatial structure with a characteristic distance separating the “cities.” In a particular case, we show that the wavelength of the dominant spatial structure is directly related to the size of an individual's information field. These effects are a consequence of interactions between individuals that arise from the nonlocalness of the information fields. We interpret the early growth stages in these models in terms of linear filters.     

Spatial Aspects of Capacity Change by U.S. Integrated Steel Producers

This paper examines changes in the location of ore-based steel-makingcapacity in the U.S. over the period 1974 to 1991 using data on each of the 45 ore-based mills that were in operation in 1974. We find that the geographic ddistributions of demand and of competition from minimills and imports were important in determining where capacity reductions occurred and which plants were closed. Technology in use at the plant also affected capacity adjustment. However, we find that regional variation in prices of raw materials were notimportant factors in determining where steel-making capacity was reduced.     

A Note on Trip Benefits in Spatial Interaction Models

We extend the well-known transport users' benefits measure (TUB) for the doubly-constrained spatial interaction model derived by Williams (1976). The original formula expresses the TUB as composed by two terms associated with the origin and the destination zones. First, the TUB is associated here with trips instead of zones, providing a natural interpretation as a rule-of-a-half measure of benefit under inelastic demand (for the short-run case). Second, a TUB formula for the long-run case is derived, that is, when the total number of trips, trip origins, and trip destinations change. We then propose updated measures of accessibility for location behavior.     

Note on the Measurement of Spatial Imbalance

This note presents a new measure of spatial imbalance that uses the center of gravity (or the mean center) of a distribution and the geometric center (or the centroid) of a region to define a vector indicating the relative position of the distribution in the region. The spatial imbalance of a distribution in a region is defined as the distance and directional deviation of the center of gravity of the distribution from the geometric center of the region. The convex hull of a region is introduced as the reference for maximum spatial imbalance of the distribution in the region. The spatial imbalance is measured in terms of (1) the relative distance of the center of gravity between the geometric center and the convex hull; and (2) the direction from the geometric center to the center of gravity. This new measure is tested by quantifying the westward movement of the contiguous U.S. population between 1790 and 1950. It describes the well‐known observation that the U.S. population was moving westward across the contiguous United States and toward reduced spatial imbalance.     

美国对以色列的政策及美以关系的发展（1948-1958）

以色列是在美国的支持下建立的。战后,美国通过插手巴勒斯坦事务,逐步从英国手中夺取处理该地区事务的主动权。在以色列建国伊始,美国给予这一新生国家巨大的帮助。但在战略上,美国并未将以色列视作特别重点考虑对象。在第二次中东战争结束以后,以色列开始受到特别关注,其在美中东战略中的地位和作用日渐突出。本文利用美国解密的档案材料及国内外学者的有关著述,对以建国初期(1948至1958年)美国对以色列的策略及美以关系的发展进行梳理与分析,希望有助于深刻理解美以特殊战略关系的形成及美以关系发展的现状。     

A Note on the Spatial Analysis of Sets of Highly Disaggregated Data

Abstract

Compared with other North American colonies, little scholarship exists on slave-holding in early Georgia. In this article, the author augments this historiography by examining a remarkable and little-used collection of sources. Data gleaned from analyzing more than 400 wills written by eighteenth-century white settlers reveal that roughly 39 percent of early Georgians owned slaves and that slave distribution was pyramidal, as most slaveholders owned but a few slaves, although some elites held many. While these findings support existing research, data from the wills suggest that early Georgia slaveholders owned, on average, about half as many slaves as other scholars contend. Besides informing an understanding of slavery in the colony, this article provides an overview of the early Georgia wills themselves, which, as sources, are highly accessible and contain a wealth of information for future scholars.