On the predictive efficiency of the core solution in side-payment games

This paper reports the first cross-study competitive test of thecore solution in side-payment games where the core is nonempty and nonunique (i.e., larger than a single point). The core was tested against five alternative theories including the Shapley value, the disruption nucleolus, the nucleolus, the 2-center, and the equality solution. A generalized Euclidean distance metric which indexes the average distance between an observed payoff vector and the entire set of predicted payoff vectors (Bonacich, 1979) was used as the measure of goodness-of-fit. Analysis of data assembled from six previously reported studies (encompassing a total of 1,464 observations over 56 3-person and 4-person side-payment games) showed the core to predict less accurately than the Shapley value, disruption nucleolus, and nucleolus solutions (p < 0.01). These findings are consistent with previous empirical results that show the core to have a low level of predictive accuracy in side-payment games.This research was supported by grants SOC-7726932 and SES-8015528 from the National Science Foundation. Data analysis was performed at the Madison Academic Computing Center.     

Defining high-performance teams and physician leadership

Learn to define the essential hallmarks of high-performing teams and look at the role of physician management in this team-based environment.     

Music and the Social Studies

The author examined the way students enrolled in the Introductory Human Geography course at Kansas State University described their hometowns using the location theme of geography. Participants completed this task as a required take-home assignment. Because the majority of students were from Kansas, the author presents results from locations of Kansas hometowns in this article. Students seemed to prefer to use relative location rather than absolute location to describe their hometowns. Realizing that expressing relative location only in one way may not be sufficient, students described relative location in numerous ways. In doing so, students provided interesting information and new insights about the place theme of geography. They also analyzed how absolute and relative location are subject to change over time. Through this assignment, students realized the importance of location and the significance of interactions of places of different sizes.     

Relationship among grip strength,functional outcomes,and work performance following hand trauma

This study examined the relationship among the recovery grip strength, functional outcomes, and work performance following occupational therapy intervention for hand trauma. This study had a sample size of 15 participants whose recovery grip strength was measured using a Jamar dynamometer, whose satisfaction with outcomes was measured by the Michigan Hand Outcomes Questionnaire (MHQ), and whose compliance with the home therapy program was measured by a visual analog scale (VAS). A Pearson r correlation demonstrated a significant relationship between recovery grip strength and two MHQ subset scores: overall hand function (r = 0.59, p = 0.019) and activities of daily living (ADL) performance (r = 0.61, p = 0.016). The participants' self-rating of compliance did not predict or influence either recovery grip strength or MHQ scores. A moderate positive correlation approaching significance (r = 0.51, p = 0.052) was found between grip strength and overall MHQ scores. The researchers concluded that a recovery grip strength measure should be used along with functional measures to appropriately assess overall hand function following hand trauma.     

Predictive superiority of the beta-characteristic function in cooperative non-sidepayment N-person games

This article reports an experimental study of decision-making outcomes in cooperative non-sidepayment games. The objective of this test was to determine which characteristic function, V (S) or V (S), provides the most accurate basis for payoff predictions from solution concepts. The experiment tested three solution concepts (core, stable set, imputation set) in the context of 5-person, 2-strategy non-sidepayment games. Predictions from each of the three solution concepts were computed on the basis of both V (S) and V (S), making a total of six predictive theories under test. Consistent with earlier studies (Michener et al., 1984a; Michener et al., 1985), two basic findings emerged. First, the data show that for each of the solutions tested, the prediction from any solution concept computed from V(S) was more accurate than the prediction from the same solution concept computed from V (S). Second, the -core was the most accurate of the six theories tested. Overall, these results support the view that V (S) is superior to V (S) as a basis for payoff predictions in cooperative non-sidepayment games.     

A test of the characteristic function and the Harsanyi function in N-person normal form sidepayment games

This paper reports the results of a laboratory experiment investigating sidepayment games represented in normal form. Attempts to predict payoff allocations via the application of solution concepts (such as the Shapley value or the nucleolus) encounter a problem in games of this form, because the game must first be transformed into some other form. Commonly, this other form is a set function defined over coalitions, such as the von Neumann-Morgenstern characteristic function. Because there are numerous possible transformations, the question arises as to which one provides the most accurate basis for prediction of payoffs.The laboratory experiment tested three such transformations - the mixed strategy characteristic function, the pure strategy characteristic function, and the Harsanyi threat function. Payoff predictions from two solution concepts (Shapley value, nucleolus) were computed on the basis of each of these transformations, making a total of six theories under test.Results of the study show, in general, that payoff predictions based on the Harsanyi threat function and on the mixed strategy characteristic function were more accurate than those based on the pure strategy characteristic function. The most accurate theories were the Shapley value computed from the Harsanyi function, the nucleolus computed from the Harsanyi function, and the Shapley value computed from the mixed strategy characteristic function. Less accurate were the nucleolus computed from the mixed strategy characteristic function and both the nucleolus and the Shapley value computed from the pure strategy characteristic function.This research was supported by grants SOC-7726932 and SES-8319322 from the National Science Foundation. The authors express appreciation to Yat-Tuck See, Jyh-Jen Horng Shiau, and Raymond Wong for assistance in computer programming, and to Jennifer Brandt, Young C. Choi, David C. Dettman, Laurel Dettman, Stephen B. Geisheker, Irving J. Ginsberg, Mike P. Griffin, Kimberly Ihm, Todd Isaacson, Christy Kinney, Mary Kohl, Sue Pope, Tammy Schmieden, Jill Schwarze, Susan Winter, and Kenneth Yuen for assistance in data collection and analysis.     

An Empirical Comparison of Probabilistic Coalition Structure Theories in 3-Person Sidepayment Games

This article reports a comparative test of the central-union theory vis-à-vis several other game-theoretic solution concepts in 3-person sidepayment games. Based on a laboratory experiment, this comparison utilizes nine games in characteristic function form. The solution concepts under test include the equal excess model, the Myerson–Shapley solution, the kernel, and two variants of the central-union theory (CU-1 and CU-2). With regard to the player's payoffs, results show that the CU-1, CU-2, kernel, and equal excess theories have essentially equal predictive accuracy and that all of these are more accurate than Myerson–Shapley. When the solution concepts are extended and coalition structure probability predictions are incorporated in the test, one version of the central-union theory (CU-2) is overall more accurate than the other solutions.     

Comparative accuracy of value solutions in non-sidepayment games with empty core

This article reports a test of the predictive accuracy of solution concepts in cooperative non-sidepayment n-person games with empty core. Six solutions were tested. Three of these were value solutions (i.e., -transfer value, -transfer nucleolus, and -transfer disruption value) and three were equilibrium solutions (deterrence set, stable set, and imputation set). The test was based on a laboratory experiment utilizing 5-person, 2-choice normal form games with empty core; other related data sets were also analyzed. Goodness-of-fit results based on discrepancy scores show that the three value solutions are about equally accurate in predicting outcomes, and that all three are substantially more accurate than the other solutions tested.