Power of the likelihood ratio test in covariance structure analysis

A procedure for computing the power of the likelihood ratio test used in the context of covariance structure analysis is derived. The procedure uses statistics associated with the standard output of the computer programs commonly used and assumes that a specific alternative value of the parameter vector is specified. Using the noncentral Chi-square distribution, the power of the test is approximated by the asymptotic one for a sequence of local alternatives. The procedure is illustrated by an example. A Monte Carlo experiment also shows how good the approximation is for a specific case.This research was made possible by a grant from the Dutch Organization for Advancement of Pure Research (ZWO). The authors also like to acknowledge the helpful comments and suggestions from the editor and anonymous reviewers.     

Lean and mean rats: Some effects of acute changes in the food supply upon territorial aggression

In experiment 1, individually housed rats subjected to short-term food restriction displayed more territorial aggression toward conspecific intruders than controls maintained on a free-feeding diet. In experiment 2, small groups of three adult male rats had access to either a standard laboratory diet or the standard diet plus sucrose. Groups with the sucrose supplement were significantly less aggressive toward intruders than controls. Sucrose availability did not produce appreciable gains in body weight but it did reliably decrease within-colony weight variation. The results suggest the existence of an effective dietary mechanism that enables a social species such as Rattus norvegicus to tolerate each other in dense feeding aggregations when food is abundant. Conversely, when food is limited, social intolerance increases and serves to limit the development of large feeding groups.     

Personality in proportion: a bipolar proportional scale for personality assessments and its consequences for trait structure

Trait structures resulting from personality assessments on Likert scales are affected by the additive and multiplicative transformations implied in interval scaling and correlational analysis. The effect comes into view on selecting a plausible alternative scale. To this end, we propose a bipolar bounded scale ranging from -1 to +1 representing an underlying process in which the assessor would review and discount positive and negative behavioral instances of a trait. As an appropriate index of likeness between variables X and Y, we propose LXY = SigmaXY/N, the average of the raw scores cross products. Using this index, we carried out a raw scores principal component analysis on data consisting of 133 participants who had each been rated by 5 assessors including self on 914 items. Contrary to the Big-Five structure that was found in these data on standard analysis, the results showed a relatively large first principal component F1 and 2 very small ones, F2 and F3. The sizes LFF=SigmaF2/N, the averages of the squared component scores, were modest to small. It thus appears that the scale, bipolar proportional versus standard, has a profound impact on the size and structure of personality assessments. The dissimilarity remains on analyzing self-ratings rather than averaged (over the 5 assessors) ratings.     

The Influence of Control on Belief in Conspiracy Theories: Conceptual and Applied Extensions

Threats to control have been found to increase belief in conspiracy theories. We argue, however, that previous research observing this effect was limited in two ways. First, previous research did not exclude the possibility that affirming control might reduce conspiracy beliefs. Second, because of artificial lab procedures, previous findings provide little information about the external validity of the control threat–conspiracy belief relationship. In Study 1, we address the first limitation and find that affirming control indeed reduces belief in conspiracy theories as compared with a neutral baseline condition. In Study 2, we address the second limitation of the literature. In a large‐scale US sample, we find that a societal threat to control, that citizens actually experienced, predicts belief in a range of common conspiracy theories. Taken together, these findings increase insight in the fundamental relationship between the human need for control and the tendency to believe in conspiracy theories. Copyright © 2015 John Wiley & Sons, Ltd.