The estimation of variance-covariance and correlation matrices from incomplete data

Employing simulated data, several methods for estimating correlation and variance-covariance matrices are studied for observations missing at random from data matrices. The effect of sample size, number of variables, percent of missing data and average intercorrelations of variables are examined for several proposed methods.The author is indebted to Professors Leonard A. Marascuilo, Gus W. Haggstrom, especially Henry F. Kaiser for their invaluable suggestions throughout this work. Appreciation is also extended to the Computer Center facility of the University of California at Berkeley for the use of computer time to complete the necessary computations.     

Feigned insanity in nineteenth-century America: Tactics,trials, and truth

Feigned insanity in nineteenth-century America is appraised through a review of the medical and legal literature. The authors focus on the explanations for feigning, procedures used in uncovering feigning, and the role of feigning in the courtroom. This discussion of feigned insanity demonstrates the remarkable consistency of approach to this form of malingering over the past 200 years.     

Human Resource Management Group,University of Nottingham,UK

In a new series of regular reports, research groups active in personnel psychology from a number of countries will present a briefing on work-in-progress. In the first in this series, the HRM Group at the Department of Psychology, University of Nottingham, describe their ongoing work into organization change and training validation, employee socialization, computer-based testing, and personality test construction and assessment centre validation.     

Intuitionistic mathematics does not needex falso quodlibet

We define a system IR of first-order intuitionistic relevant logic. We show that intuitionistic mathematics (on the assumption that it is consistent) can be relevantized, by virtue of the following metatheorem: any intuitionistic proof of A from a setX of premisses can be converted into a proof in IR of eitherA or absurdity from some subset ofX. Thus IR establishes the same inconsistencies and theorems as intuitionistic logic, and allows one to prove every intuitionistic consequence of any consistent set of premisses.This paper grew out of discussion of a survey talk, on earlier work, that I gave to the 5th A.N.U. Paraconsistency Conference in January 1988. I am greatly indebted to the suggestion by Michael MacRobbie on that occasion that I investigate the so-called non-Ketonen form of the sequent rule for on the right. That suggestion inspired the correspondingly modified rule of Introduction in the system of natural deduction given above.     

Privacy and the Human Genome Project

The Human Genome Project has raised many issues regarding the contributions of genetics to a variety of diseases and societal conditions. With genetic testing now easily conducted with lowered costs in nonmedical domains, a variety of privacy issues must be considered. Such testing will result in the loss of significant privacy rights for the individual. Society must now consider such issues as the ownership of genetic data, confidentiality rights to such information, limits placed on genetic screening, and legislation to control genetic testing and its applications. There is often a conflict between individual rights to privacy and the need for societal protection.     

Sentencing severity with mock jurors: Predictive validity of three variable categories

Previous studies have identified three categories of variables which influence decisions of mock jurors: type of crime, defendant characteristics, and personal characteristics of jurors. This study manipulated the following variables towards the ends of assessing their influence on mock jurors' sentencing severity: premeditated vs. unpremeditated murder, black vs. white defendant, low SES vs. high SES defendant. Only defendant SES predicted sentencing severity: low SES defendants were assigned significantly longer sentences than high SES defendants. None of the measures of juror characteristics correlated with sentencing severity. Failure to replicate significant relationships with most of these variables and sentencing severity suggest that results of studies which manipulate only one variable dimension may overestimate the influence of these variable dimensions in mock jurors' decisions.     

Sex differences in impulsivity and intellectual ability

Literature on sex differences in impulsivity has tended to focus on differences between groups, while ignoring relationships beyond zero order correlations. The purpose of this study was to evaluate Maccoby's hypothesis (1966) of opposite-direction correlations where the relationship between a set of variables (e.g., impulsivity and intellectual ability) is curvilinear, with males and females being systematically distributed on opposite sides of the curve. The Primary Mental Abilities (PMA) and Matching Familiar Figures tests were administered to 44 males and 49 females. The relationship between all of the PMA subtests and impulsivity was curvilinear for males, but linear for females on all but one of the subtests. The importance and implications of examining distribution differences rather than group differences are discussed.Support for this study has come from the Office of Research Administration, University of Kansas, Grant Number 3581-5038. This paper was presented in part at the meeting of the American Psychological Association, Chicago, August 1975, Division 7.     

Tables of d′ for variable-standard discrimination paradigms

Signal detection theory (SDT) allows a bias-free measure of sensitivity, d′, to be simply estimated from discrimination data when certain conditions are met. The computation is not straightforward, however, in several popular discrimination designs, such as two- and four-interval same-different designs and the ABX design. The present tables, derived from the SDT models of Macmillan, Kaplan, and Creelman (1977), make possible the estimation of d’ from these complex discrimination designs.     

Effect of effort and latent extinction on resistance to extinction

Sixty-four male Wistar rats were given acquisition training in an enclosed straight-alley runway which could be adjusted for angles of inclination. The 2×2×2 design involved two angles of inclination in acquisition (0° and 40°) and two angles of inclination in extinction (0° and 40°). Between acquisition and extinction, half the subjects were exposed to a latent extinction procedure and half served as controls. Number of responses in a 30-min extinction session was an inverse function of effort required in extinction. Additionally, latent extinction procedures resulted in reduced resistance to extinction, but only when the effort conditions of acquisition and extinction were constant. When the effort conditions of acquisition and extinction were dissimilar, latent extinction procedures resulted in increased resistance to extinction. The results raise questions about the nature of the learning which occurs during latent extinction training.     

A system for the assessment of human performance in concurrent verbal and manual control tasks

A multipurpose laboratory system incorporating a voice interactive terminal and graphic display system is described. The facility is designed to investigate some aspects of human performance on concurrent verbal and tracking tasks. The results of a pilot study showing decrements in dual-task performance are reported.