Independent dominating sets in triangle-free graphs

The independent domination number of a graph is the smallest cardinality of an independent set that dominates the graph. In this paper we consider the independent domination number of triangle-free graphs. We improve several of the known bounds as a function of the order and minimum degree, thereby answering conjectures of Haviland.     

Cortisol Rise Following Awakening Among Problem Gamblers: Dissociation from Comorbid Symptoms of Depression and Impulsivity

Gambling pathology has been associated with elevated levels of distress, depression and impulsivity. The present investigation assessed whether these behavioral features would be evident among problem gamblers as they are among pathological gamblers. As well, given that gambling has been associated with increased life stress, as an objective index of ongoing distress, elevations of morning cortisol levels were assessed in problem and pathological gamblers relative to recreational gamblers, and their relations to depressive symptoms and impulsivity were assessed. Recreational, problem, and pathological gamblers (N = 140) completed the Beck Depression Inventory and the Barratt Impulsiveness Scale-11, and provided saliva samples at awakening, 30 min, 3.5 h, and 5.5 h afterward. Consistent with the view that problem and pathological gambling are associated with elevated life stressors, the rise of morning cortisol from awakening to 30 min following awakening was greater than in recreational gamblers. Heightened impulsivity was evident among both problem and pathological gamblers, whereas depressive symptoms were only evident among pathological gamblers. In neither instance were these psychological indices related to the morning cortisol rise. Indeed, increased depressive symptoms were not evident among problem gamblers, despite the fact that elevated morning cortisol levels were evident. The elevated morning cortisol rise may be secondary to gambling problems or distress related to gambling problems. Furthermore, the sustained morning cortisol elevations may be indicative of allostatic overload, and could potentially be a harbinger for potential health risks among problematic gamblers.     

Christian Fundamentalists and Public Opinion Toward the Middle East: Israel's New Best Friends?*

Objectives. Although Christian fundamentalist elites have become increasingly vocal in their support for Israel in the ongoing conflict in the Middle East, it is not clear that this rhetoric has produced differing attitudes about U.S. foreign policy in public opinion. This article examines whether such differences exist, and whether they are rooted in aspects of fundamentalist eschatology. Methods. Data from a national telephone survey on attitudes toward the Middle East conflict and U.S. policy were examined using multivariate regression and means comparisons. Results. These results demonstrate that Christian fundamentalists are the strongest supporters of Israel in America today. Fundamentalists have greater sympathy for Israel, oppose policies to pressure Israel, and are distinctive from all other groups in their high levels of support for continuing Israeli settlements in occupied Palestinian territories, as well as complete Israeli control of Jerusalem. Conclusion. Christian fundamentalists in America are distinctive on this vital issue in American foreign policy because of their literal interpretation of the Bible or their leaders' increased cues on Middle East policies, or both. This suggests that religion is now an important factor in understanding public opinion on U.S. foreign policy in the region.     

Properties of maximum likelihood estimates of the ratio of parameters in ordinal response regression models

The properties of a method of estimating the ratio of parameters for ordered categorical response regression models are discussed. If the link function relating the response variable to the linear combination of covariates is unknown then it is only possible to estimate the ratio of regression parameters. This ratio of parameters has a substitutability or relative importance interpretation.

The maximum likelihood estimate of the ratio of parameters, assuming a logistic function (McCullagh, 1980), is found to have very small bias for a wide variety of true link functions. Further it is shown using Monte Carlo simulations that this maximum likelihood estimate, has good coverage properties, even if the link function is incorrectly specified. It is demonstrated that combining adjacent categories to make the response binary can result in an analysis which is appreciably less efficient. The size of the efficiency loss on, among other factors, the marginal distribution in the ordered categories     

MARCH MADNESS? UNDERREACTION TO HOT AND COLD HANDS IN NCAA BASKETBALL

The hot hand bias is the widely documented bias toward overestimation of positive serial correlation in sequential events. We test for the hot hand bias in a novel real‐world context, the seeding of National Collegiate Athletic Association (NCAA) basketball tournament teams. That is, we examine whether teams that perform relatively well heading into “March Madness” are seeded too high, and/or teams with poor recent performance are seeded too low. The seeds are determined by a 10‐member committee that only has implicit incentives, but these incentives are still substantial as the committee's decisions are highly scrutinized by the media, fans, and other stakeholders. We find that, contra the hot hand bias, the committee underreacts to signals of momentum heading into the NCAA tournament. Various results indicate this behavior can be attributed to both: (1) inattention to relatively detailed information indicating momentum; and (2) under‐appreciation of the predictive value of this information. Betting markets incorporate this information efficiently, but neglect some additional information that is predictive of winning NCAA tournament games but not of beating the spread. We note that the NCAA tournament has been highly popular and lucrative partly due to the “madness” (high frequency of wins by lower‐seeded teams), which the bias we document contributes to, making the persistence of bias less surprising. (JEL D83, L83)     

JOBLESS RECOVERIES: STAGNATION OR STRUCTURAL CHANGE?

Within the existing literature a number of competing explanations for jobless recoveries have emerged. On the one hand there is evidence of dynamic structural change including offshoring/globalization and technological advances that are resulting in the loss of middle‐skill (routine) employment. Other studies emphasize a less dynamic economy with slower growth, reduced labor market fluidity, a decline in startup activity, and even economic stagnation. This study exploits variation among U.S. states to assess the degree that stagnation and/or important structural changes in the economy contribute to the recent phenomenon of jobless recoveries. We find support for both the stagnation and structural change theories of jobless recoveries. On the stagnation side, we find evidence that lower startup rates are a significant predictor of jobless recoveries. We also find evidence that links dynamic structural change to the jobless recovery phenomenon. More specifically states experiencing a long‐run downward trend in the share of routine employment are more likely to experience a jobless recovery. Our results are consistent with the polarization theory where routine‐replacing technological advances permanently reduce demand for middle‐skill labor, thus contributing to jobless recoveries. (JEL E32, E24)