Permutational Multiple Testing Adjustments With Multivariate Multiple Group Data

We consider the multiple comparison problem where multiple outcomes are each compared among several different collections of groups in a multiple group setting. In this case there are several different types of hypotheses, with each specifying equality of the distributions of a single outcome over a different collection of groups. Each type of hypothesis requires a different permutational approach. We show that under a certain multivariate condition it is possible to use closure over all hypotheses, although intersection hypotheses are tested using Boole's inequality in conjunction with permutation distributions in some cases. Shortcut tests are then found so that the resulting testing procedure is easily performed. The error rate and power of the new method is compared to existing competitors through simulation of correlated data. An example is analyzed, consisting of multiple adverse events in a clinical trial.     

Optimal caliper widths for propensity-score matching when estimating differences in means and differences in proportions in observational studies

In a study comparing the effects of two treatments, the propensity score is the probability of assignment to one treatment conditional on a subject's measured baseline covariates. Propensity-score matching is increasingly being used to estimate the effects of exposures using observational data. In the most common implementation of propensity-score matching, pairs of treated and untreated subjects are formed whose propensity scores differ by at most a pre-specified amount (the caliper width). There has been a little research into the optimal caliper width. We conducted an extensive series of Monte Carlo simulations to determine the optimal caliper width for estimating differences in means (for continuous outcomes) and risk differences (for binary outcomes). When estimating differences in means or risk differences, we recommend that researchers match on the logit of the propensity score using calipers of width equal to 0.2 of the standard deviation of the logit of the propensity score. When at least some of the covariates were continuous, then either this value, or one close to it, minimized the mean square error of the resultant estimated treatment effect. It also eliminated at least 98% of the bias in the crude estimator, and it resulted in confidence intervals with approximately the correct coverage rates. Furthermore, the empirical type I error rate was approximately correct. When all of the covariates were binary, then the choice of caliper width had a much smaller impact on the performance of estimation of risk differences and differences in means.     

Modular Network Design: Using Information and Communication Technology to Allocate Production Tasks in a Virtual Organization*

The increased interest in customer service and the trend towards customization gives rise to new organizational forms such as the virtual organization. This paper introduces the Modular Network Design (MND) approach to complement Mowshowitz' (1997) theory of virtual organization. This theory focuses on metamanagement of the virtual organization and consists of four activities: (1) determine and analyze customer requirements, (2) track the possibilities for satisfying these requirements, (3) develop and allocate production tasks among the members of the virtual organization, and (4) assess and adjust tasks and allocation procedures. The MND approach elaborates on this theory by breaking down both the requirements and the production tasks into modular entities, and by measuring the performance of the resulting virtual network in terms of operating costs and throughput time. The major contribution of the MND approach lies in its ability to support the assessment of alternative allocations of production tasks among the members of a virtual organization, using Information and Communication Technology (ICT) as enabler. The assessment of such alternative designs is illustrated by an application of MND in the air cargo industry. The results show how the virtual organization and its members can realize significant improvements in operating costs and throughput times when applying ICT to link and reallocate their modular production tasks in response to customized orders.     

A Demonstration of Methods for Studying Negotiations Between Physicians and Health Care Managers*

Decision analysis was used to study negotiations in the health care context. This paper found that analytical methods could answer several important questions related to complex negotiations, including whether contracts promote the interest of both parties, whether a decision aid could better meet the priorities of both parties, and whether one negotiator is more successful than the other in repeated negotiations. The paper concluded that micro-health care negotiations can be traced and studied with existing mathematical theories of negotiation.     

How Believing in Ourselves Increases Risk Taking: Perceived Self-Efficacy and Opportunity Recognition

What effect does positive and negative feedback about past risk taking have on the future risk taking of decision makers? The results of an experimental study show that subjects who are led to believe they are very competent at decision making see more opportunities in a risky choice and take more risks. Those who are led to believe they are not very competent see more threats and take fewer risks. The feelings of self-competence and self-confidence on one task did not generalize to a similar task. Perception of opportunities was unexpectedly not related to the perception of threats. As executives bring their personal perceptual biases to firm decision making, our results identify a serious built-in bias in SWOT analysis (the analysis of firms' strengths and weaknesses as related to potential opportunities and threats). Executives who believe that they and their firm are very competent will take more risks and vice versa. Our results also provide evidence that the perceived likelihood of an event depends on whether the event is a loss or a gain. Human decision making is subject to the general bias that outcome expectations are not independent of outcome valuations.     

Planning Service Capacity When Demand Is Sensitive to Delay

This paper presents a model designed to help determine the number of clerks or servers in a retail queuing situation. The model demonstrates a realistic treatment of the effect of waiting time on customer demand and revenues by treating the average waiting time as a form of price. Thus, the demand rate and service level are interrelated. The number of servers is obtained by balancing the cost of additional servers against the revenues and profits arising from greater demand. An example is shown, using data obtained from a supermarket, to demonstrate the insight gained from applying the model. Some extensions and research possibilities are considered, including a treatment of ancillary activities. An appendix examines a continuous version of the model which provides additional insight into the character of the model.     

Anti-homosexual prejudice . . . as opposed to what? Queer theory and the social psychology of anti-homosexual attitudes

This article uses Sedgwick's distinction between minoritizing and universalizing theories of sexuality to analyze variability in social psychologists' studies of anti-homosexual prejudice, focusing on studies of attitudes. Anti-homosexual prejudice was initially defined in conversation with gay liberationists and presumed, among other things, that fear of homoerotic potential was present in all persons. Later social psychologists theorized anti-homosexual prejudice in strict minoritizing terms: as prejudice towards a distinct out-group. In the first section of this paper we discuss corresponding shifts in the conceptualization of anti-homosexual attitudes. Next, using a universalizing framework, we re-interpret experiments on behavioral aspects of anti-homosexual attitudes which were originally conceptualized using a minoritizing framework, and suggest avenues for future research. Finally, we examine how queer theory might enrich this area of social psychological inquiry by challenging assumptions about the politics of doing scientific work and the utility of identity-based sexual politics.     

Can one TV show make a difference? Will & Grace and the Parasocial Contact Hypothesis

Television has an opportunity to influence beliefs about groups with which individuals typically may have little direct social contact. This study describes a synthesis of the Contact Hypothesis and the concept of Parasocial Interaction to pose what we call the Parasocial Contact Hypothesis to test whether exposure to gay men on Will & Grace can influence attitudes toward gay men in general. Based on a study of 245 university students, this study examines the relationships among number and intimacy of gay social contacts, parasocial interaction, viewing frequency of Will & Grace, and scores on Herek's Attitudes Toward Gay Men and Lesbians scale. Increased viewing frequency and parasocial interaction were found to correlate with lower levels of sexual prejudice-a relationship that was most pronounced for those with the least amount of social contact with lesbians and gay men.     

24/7 SM slavery

This study describes the nature of 24/7 SM slavery as practiced within the SM (sadomasochistic) community. These SM participants, who attempt to live full-time in owner-slave roles, represent a small proportion of those with SM interests. SM slaves have not been studied systematically to determine if and how they differ from other SM practitioners. An online questionnaire was used to obtain responses from individuals who self-identified as slaves. A total of 146 respondents participated, 53% female and 47% male, ranging in age from 18 to 72. We explored the depth of their relationships, how well they approximated "slavery," and how their relationships were structured to maintain distinct roles. Data showed that in long-term SM slave relationships, a power differential exists which extends beyond time-limited SM or sexual interactions. Owners and slaves often use common, daily life experiences or situations, such as the completion of household chores, money management, and morning or evening routines, to distinguish and maintain their respective roles. In addition, contrary to the perception of total submission, results revealed that slaves exercise free will when it is in their best interests to do so. These relationships were long-lasting and satisfying to the respondents.