Jorge L. Mendoza

A step-down hierarchical multiple regression analysis for examining hypotheses about test bias in prediction

The problem of determining test bias in prediction using regression models is reexamined. Past ap proaches have made use of separate regression anal yses in each subgroup, moderated multiple regression analysis using subgroup coding, and hierarchical mul tiple regression strategies. Although it is agreed that hierarchical multiple regression analysis is preferable to either of the former methods, the approach pre sented here differs with respect to the hypothesis test ing procedure to be employed in such an analysis. This paper describes the difficulties in testing hy potheses about the existence of bias in prediction us ing step-up methods of analysis. Some shortcomings of previously recommended approaches for testing these hypotheses are discussed. Finally, a step-down hierarchical multiple regression procedure is recom mended. Analysis of real data illustrates the potential usefulness of the step-down procedure.

Maintenance of safer sexual behaviours: evaluation of a theory‐based intervention for HIV seropositive men with haemophilia and their female partners

A theory‐based HIV risk‐reduction intervention was developed for HIV‐positive men with haemophilia and their HIV‐negative female romantic partners. The intervention was based on Prochaska and DiClemente’s Transtheoretical Model which describes behaviour change as an incremental, stage‐based process. The intervention targeted both communication about safer sex and safer sex behaviours (consistent condom use or abstinence from vaginal intercourse). A total of 255 males and 158 females from six funded haemophilia treatment centres or patient organizations (and 27 associated subsites) participated in the study. Baseline and follow‐up (15 months after baseline) measures were administered to assess safer sexual behaviours, communication about safer sex and condom self‐efficacy. A quasi‐experimental, repeated measures design was utilized to compare two naturally occurring groups; those who received the full intervention package and those who received incomplete or no intervention components. Significant intervention effects for safer sex behaviours, communication about safer sex and condom self‐efficacy were identified for the male participants, with those receiving the full intervention package demonstrating better outcomes at follow‐up. Women who received the full intervention package were more likely to report the use of a condom by their male partner during the last act of vaginal intercourse.

Validation of an instrument to measure service-orientation

Abstract Hogan, Hogan, and Busch (1984: 167) define service-orientation as “the disposition to be helpful, thoughtful, considerate, and cooperative.” To measure this construct they developed the Service Orientation Index (SOI), an 87-item true false questionnaire. The purpose of the present study was to test whether or not a biodata inventory could also be used to measure the service-orientation construct. Subjects were given the inventory in order to predict their service-oriented performance in a simulated customer interaction. The service-orientation ratings were consistently highly correlated with three topical scales: “the need to make a good impression,” “sociability,” and “helpfulness.” The correlations of these scales with service-orientation were as high or higher than those generally obtained with the SOI; and thus, it was concluded that service-orientation may effectively be measured by biodata.

The Collective Behavior of Fads: The Characteristics, Effects, and Career of Streaking

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Confidence Intervals, Power Calculation, and Sample Size Estimation for the Squared Multiple Correlation Coefficient under the Fixed and Random Regression Models: A Computer Program and Useful Standard Tables

In this article, the authors introduce a computer package written for Mathematica, the purpose of which is to perform a number of difficult iterative functions with respect to the squared multiple correlation coefficient under the fixed and random models. These functions include, among others, computation of confidence interval upper and lower bounds, power calculation, calculation of sample size required for a specified power level, and providing estimates of shrinkage in cross validating the squared multiple correlation under both the random and fixed models. Attention is given to some of the technical issues regarding the selection of, and working with, these two types of models as well as to issues concerning the construction of confidence intervals.

Corrections for attenuation and range restriction on the predictor.

Researchers often need to obtain an estimate of the relationship between a predictor and a criterion under conditions where the magnitude of the correlation coefficient has been distorted by an error component in the predictor and criterion variables (attenuation) and restriction in the range of the predictor. The present paper delineates the factors that influence the joint impact of attenuation and range restriction on the magnitude of the correlation coefficient, and establishes a theoretical framework for the generation of appropriate correction formulas. A set of equations for making joint attenuation and range restriction corrections when there is attenuation and restriction on the predictor is presented. Finally, it is shown that the concept of predictor reliability changes in selection situations because of the correlation between error and true scores.

Development of a Biodata Index to Measure Service-Orientation

In 1984 Hogan, Hogan, and Busch defined service-orientation as “the disposition to be helpful, thoughtful, considerate, and cooperative” (p. 167). As a measure they developed the Service Orientation Index, a 92-item true-false questionnaire. The present study tested whether a biographical inventory could also be used to measure the construct of service-orientation. Subjects were given the biographical inventory and the Index to predict their service-oriented performance in a simulated interaction with a customer. Scores on the Service orientation Index were significantly correlated with scores on two biographical scales, Sociability and the Need to make a good impression. The correlations, .24 and .27, were as high as those obtained by Hogan, et al. The Index scores were also significantly correlated with the criterion. Subjects with high scores on Sociability and the Need to make a good impression had the highest ratings on service-orientation. Implications for research and applications of these results are mentioned.

A New Perspective on Sequential Testing Procedures in Canonical Analysis: A Monte Carlo Evaluation.

A Monte Carlo study was conducted in order to compare four testing procedures in establishing the number of nonzero population roots in a canonical analysis. Three of the methods investigated were sequential testing methods which have lately fallen under heavy criticism. The fourth method was a test advocated by Harris (1976) to be a more appropriate test. Results demonstrated the effectiveness of the sequential testing procedures and the relative ineffectiveness of the Harris method. The conclusion was that the criticisms aimed at the sequential testing for nonzero roots in canonical analysis are simply not well-founded.

What counts as evidence for working memory training? Problems with correlated gains and dichotomization

The question of whether computerized cognitive training leads to generalized improvements of intellectual abilities has been a popular, yet contentious, topic within both the psychological and neurocognitive literatures. Evidence for the effective transfer of cognitive training to nontrained measures of cognitive abilities is mixed, with some studies showing apparent successful transfer, while others have failed to obtain this effect. At the same time, several authors have made claims about both successful and unsuccessful transfer effects on the basis of a form of responder analysis, an analysis technique that shows that those who gain the most on training show the greatest gains on transfer tasks. Through a series of Monte Carlo experiments and mathematical analyses, we demonstrate that the apparent transfer effects observed through responder analysis are illusory and are independent of the effectiveness of cognitive training. We argue that responder analysis can be used neither to support nor to refute hypotheses related to whether cognitive training is a useful intervention to obtain generalized cognitive benefits. We end by discussing several proposed alternative analysis techniques that incorporate training gain scores and argue that none of these methods are appropriate for testing hypotheses regarding the effectiveness of cognitive training.

Fisher Transformations for Correlations Corrected for Selection and Missing Data.

The validity of a test is often estimated in a nonrandom sample of selected individuals. To accurately estimate the relation between the predictor and the criterion we correct this correlation for range restriction. Unfortunately, this corrected correlation cannot be transformed using FishersZ transformation, and asymptotic tests of hypotheses based on small or moderate samples are not accurate. We developed a Fisherr toZ transformation for the corrected correlation for each of two conditions: (a) the criterion data were missing due to selection on the predictor (the missing data were MAR); and (b) the criterion was missing at random, not due to selection (the missing data were MCAR). The twoZ transformations were evaluated in a computer simulation. The transformations were accurate, and tests of hypotheses and confidence intervals based on the transformations were superior to those that were not based on the transformations.