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Superior Power (superior + power)

Distribution by Scientific Domains

Business, Economics, Finance and Accounting	50%

Selected Abstracts

A partial least-square approach for modeling gene-gene and gene-environment interactions when multiple markers are genotyped

GENETIC EPIDEMIOLOGY, Issue 1 2009
Tao Wang
Abstract Genetic association studies achieve an unprecedented level of resolution in mapping disease genes by genotyping dense single nucleotype polymorphisms (SNPs) in a gene region. Meanwhile, these studies require new powerful statistical tools that can optimally handle a large amount of information provided by genotype data. A question that arises is how to model interactions between two genes. Simply modeling all possible interactions between the SNPs in two gene regions is not desirable because a greatly increased number of degrees of freedom can be involved in the test statistic. We introduce an approach to reduce the genotype dimension in modeling interactions. The genotype compression of this approach is built upon the information on both the trait and the cross-locus gametic disequilibrium between SNPs in two interacting genes, in such a way as to parsimoniously model the interactions without loss of useful information in the process of dimension reduction. As a result, it improves power to detect association in the presence of gene-gene interactions. This approach can be similarly applied for modeling gene-environment interactions. We compare this method with other approaches, the corresponding test without modeling any interaction, that based on a saturated interaction model, that based on principal component analysis, and that based on Tukey's one-degree-of-freedom model. Our simulations suggest that this new approach has superior power to that of the other methods. In an application to endometrial cancer case-control data from the Women's Health Initiative, this approach detected AKT1 and AKT2 as being significantly associated with endometrial cancer susceptibility by taking into account their interactions with body mass index. Genet. Epidemiol. 2008. © 2008 Wiley-Liss, Inc. [source]

Image Theory, Social Identity, and Social Dominance: Structural Characteristics and Individual Motives Underlying International Images

POLITICAL PSYCHOLOGY, Issue 1 2005
Michele G. Alexander
The present study provides an empirical test of international relations image theory and extends the theory by emphasizing that individuals' social identity and social dominance motives contribute to such images. One hundred forty-five Lebanese participants completed a survey that assessed their perceptions of U.S.-Lebanese relations, the images they have of the United States, their social identities, and their social dominance orientations. Participants were more likely to hold the barbarian image of the United States than the enemy, imperialist, or ally images. Participants also tended to perceive the United States as having relatively superior power, inferior cultural status, and goals that are incompatible with those of Lebanon. Consistent with image theory predictions, this constellation of structural perceptions was associated with stronger endorsement of the barbarian image. Furthermore, participants were more likely to endorse the barbarian image of the United States the more they identified with Arabs and Palestinians, the less they identified with Christians and the Western world, and the lower their social dominance orientation. Results highlight the importance of considering both structural characteristics and individual motives underlying international images and demonstrate the need for scholars to move beyond the enemy image of nations when describing international relations. [source]

Seasonal unit root tests and the role of initial conditions

THE ECONOMETRICS JOURNAL, Issue 3 2008
David I. Harvey
Summary, In the context of regression-based (quarterly) seasonal unit root tests, we examine the impact of initial conditions (one for each quarter) of the process on test power. We investigate the behaviour of the well-known OLS detrended HEGY seasonal unit root tests together with their quasi-differenced (QD) detrended analogues, when the initial conditions are not asymptotically negligible. We show that the asymptotic local power of a test at a given frequency depends on the value of particular linear (frequency specific) combinations of the initial conditions. Consistent with previous findings in the nonseasonal case, the QD detrended test at a given spectral frequency dominates on power for relatively small values of this combination, while the OLS detrended test dominates for larger values. Since, in practice, the seasonal initial conditions are not observed, in order to maintain good power across both small and large initial conditions, we develop tests based on a union of rejections decision rule; rejecting the unit root null at a given frequency (or group of frequencies) if either of the relevant QD and OLS detrended HEGY tests rejects. This procedure is shown to perform well in practice, simultaneously exploiting the superior power of the QD (OLS) detrended HEGY test for small (large) combinations of the initial conditions. Moreover, our procedure is particularly adept in the seasonal context since, by design, it exploits the power advantage of the QD (OLS) detrended HEGY tests at a particular frequency when the relevant initial condition is small (large) without imposing that same method of detrending on tests at other frequencies. [source]

Relative power and influence strategy: the effects of agent/target organizational power on superiors' choices of influence strategies

JOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 2 2002
Anit Somech
The present study examined superiors' tendency to utilize different top,down influence strategies according to their evaluation of their own power relative to that of their subordinates. Four hundred and fifty-five subordinates (schoolteachers) from different schools described the extent to which their superiors used each item of the influence strategy questionnaire to influence them, while their immediate superiors evaluated superior's power and subordinate's power. Overall, superiors tended to use soft and rational strategy more often than hard strategy. However, regarding the parameter of relative power, the results indicated that the agent's power, as well as the target's power, affected the superior's choice of particular influence strategy. The results suggest that power should be discussed in relative rather than absolute terms. Copyright © 2001 John Wiley & Sons, Ltd. [source]