We present a simulation technique for sorting out the size, shape, and location of the uncovered set to estimate the set of enactable outcomes in “real-world” social choice situations, such as the contemporary Congress. The uncovered set is a well-known but underexploited solution concept in the literature on spatial voting games and collective choice mechanisms. We explain this solution concept in nontechnical terms, submit some theoretical observations to improve our theoretical grasp of it, and provide a simulation technique that makes it possible to estimate this set and thus enable a series of tests of its empirical relevance.

This article promotes a characterization of intraparty politics that explains how rank- and-file party members control the delegation of power to their cabinet ministers and shadow cabinet ministers. Using the uncovered set as a solution concept and a measure of party members' collective preferences, we explore the hypothesis that backbenchers' preferences constrain the ministerial selection process in a manner that mitigates agency problems. Specifically, promotion is distributed preferentially to members whose own policy preferences are proximate to the uncovered set of all party members' preferences. Our analysis of ministerial appointments in the contemporary British Parliament supports this view. For both the Labour and Conservative parties, front bench appointments are more sensitive to the collective preferences of backbenchers in each party as measured by the party uncovered set than to the preferences of the parties' leaders.

The antibody responses of 8 cattle experimentally infected with Onchocerca ochengi to 18 recombinant O. volvulus antigens were measured by ELISA. In addition to establishing antigenic cross-reactivity between the species, the dynamics of antigen-specific responses were examined to assess how the recognition of the antigens compared to the known stage-specificity of expression. Six cattle responded to all of the antigens and 2 animals responded to all but 1. The dynamics of the recognition of 4 antigens (B20, MOv-2, MOv-14 and OvNHR2 02E1) were characterized by rapid seroconversion following infection. Antibody levels to 2 antigens (Ov7 and OvALT-1) increased gradually over the course of infection. Antibody levels to 4 antigens (OvTPX-2, OvL3Chitinase, Ov103 and Ov9m) reached maximum levels coincident with the onset of patency. The levels to 3 antigens (OvProalf C50, OvAldolase, Ov39) varied little over the course of infection. Responses to antigens with functional similarities (OvSOD1, OvSOD2 and OvSOD3 or OvGST1 and OvGST2) showed comparable temporal profiles. This study demonstrates the high degree of immunological cross-reactivity between the antigens of O. volvulus and O. ochengi. The immunogenicity of antigens varied over the course of infection in an antigen-specific manner, which not always reflected developmentally regulated expression of the corresponding gene, possibly owing to cross-reactive epitopes on distinct parasite products.

Adult males and females of Onchocerca gutturosa were implanted into the peritoneal cavity of mice, and their survival was determined at intervals thereafter by post-mortem examination. Ten of 17 animals receiving males dissected free of bovine host tissues contained live parasites at necropsy up to 4 months later. Female worms digested free from connective tissue by collagenase did not survive well, even though they appeared motile and intact before implantation; only 2 were alive 10 days later in 2 of 16 recipients. When males and females still contained within connective tissue capsules were implanted they survived for up to 2 months, and microfilariae were detected transiently in the skin of 2 recipient mice. The results suggest the feasibility of maintaining adult O. gutturosa in rodents by this means, provided exposure of worms to enzymes used to free them from host tissue is avoided.

The uncovered set has frequently been proposed as a solution concept for majority rule settings. This paper tests this proposition using a new technique for estimating uncovered sets and a series of experiments, including five-player computer-mediated experiments and 35-player paper-format experiments. The results support the theoretic appeal of the uncovered set. Outcomes overwhelmingly lie in or near the uncovered set. Furthermore, when preferences shift, outcomes track the uncovered set. Although outcomes tend to occur within the uncovered set, they are not necessarily stable; majority dominance relationships still produce instability, albeit constrained by the uncovered set.

This paper aims at enriching the debate over the measurement of majority party influence in contemporary American legislatures. Our use of a new analytic technique, a grid-search program for characterizing the uncovered set, enables us to begin with a better model of legislative proceedings that abandons the simple one-dimensional spatial models in favor of the more realistic two-dimensional version. Our conclusions are based on the analysis of real-world data rather than on arguments about the relative merits of different theoretic assumptions. Our analysis confirms that when legislators' preferences are polarized, outcomes will generally be closer to the majority party's wishes, even if the majority-party leadership does nothing to influence the legislative process. This conclusion notwithstanding, our analysis also shows that at the margin of the majority party's natural advantage, agenda setting by the majority party remains a viable and efficacious strategy.

The Movers and the Shirkers is a critique and extension of awell-cited and important research program: attempts tomeasure the degree to which legislators shirk, or advancetheir own policy goals at the expense of those held by theirconstituents. Such analyses (e.g., Joseph P. Kalt and MarkZupan, "Capture and Ideology in the Economic Theory ofPolitics," American Economic Review 74 [June 1984]: 279­300; John R. Lott, "Political Cheating," Public Choice 52[1987]: 169­86) typically assume a principal-agent relation-ship between constituents and elected representatives, andthey specify a regression analysis with roll-call behavior as aleft-hand side variable and various measures of constituencyinterests and legislator ideology as right-hand side variables.Previous work (John E. Jackson and John W. Kingdon,"Ideology, Interest Groups, and Legislative Votes," AmericanJournal of Political Science 36 [August 1992]: 805­23) showsthat these analyses are bedeviled by measurement and esti-mation issues. Eric Uslaner highlights a more fundamentalflaw: By ignoring important and well-understood mechanismsthat tie legislators to their constituents, these analyses as-sume what should be tested.

This paper critiques the expectation that informative legislative committees, those that provide policy-relevant information to their parent body, will be “microcosms of their parent chamber” (Krehbiel 1991, 95), with the median committee ideal point close to the floor median and remaining ideal points distributed about the committee median. Drawing on the concept of cue-taking (Matthews and Stimson 1975), I show that a similarity of medians is not necessary for a committee to inform its parent body; a nonmedian committee can easily perform this function if the right mix of legislators is appointed. However, heterogeneity is found to be a critical factor in facilitating a committee's informational role. Accordingly, comparisons of committee and floor medians designed to identify informative committees may lead scholars to incorrect conclusions. The final section of the paper uses this intuition to reevaluate Krehbiel's (1990) and Hall and Grofman's (1990) analysis of committees in the 99th Congress.

George Tsebelis argued in the March 1989 issue of this Review that decision theory is completely appropriate for analyzing games against nature but not appropriate for dissecting games against a rational opponent. Analysts who mistake a rational opponent for nature in constructing models commit what Tsebelis calls “the Robinson Crusoe fallacy.” In this controversy, William Bianco and Peter Ordeshook attack components of Tsebelis's argument. Bianco believes the model should be set up as an iterated, rather than a one-shot, game. Ordeshook feels that proper modeling cannot rely merely on two-person games and, in addition, he argues that Tsebelis commits some technical errors. In his reply, Tsebelis joins the issues and buttresses his original analysis.

We return to the analysis of cooperation among interdependent rational individuals. We emphasize the limited impact of iteration (or repeated play) and explore the possibility of an alternative: intervention by rational agents, whom we call leaders. We show that leadership is more significant for initiating cooperation than for sustaining it. In addition, we identify two features of organizations that are critical in determining a leader's ability to initiate and sustain cooperation by structuring the incentives of his followers: the leader's capabilities (information and strategy sets) and reward structure (payoff function).

The current understanding of vote trading assumes legislators' payoffs vary only with results—the motions enacted or defeated by their votes. This characterization is not supported by evidence from the modern Congress. This paper specifies a model of vote trading in which legislators' payoffs are a function of results and voting behavior. Analysis of this game amends the standard wisdom about voting and vote trading in two areas: the existence of a nonempty core, and the conditions under which sophisticated voting produces an outcome in the core.

We propose measuring group support for political parties by means of multivariate techniques that have become standard in other areas of political behavior. This approach yields improved insights into the marginal difference made by membership in each group and into the nature of a party's support coalition. As an example of this approach, we analyze the Democratic coalition since 1952. Our results differ from those of previous studies in a number of ways. Most significantly, differences with respect to the strength and timing of partisan changes lend support to Carmines and Stimson's conclusion that a realignment centering on race occurred in the mid-1960s. Our findings also indicate that the Democratic party is no longer so dependent on a few groups, as it was in the 1950s, but is now almost equally dependent on six groups.