Alternative procedures for testing regression slope homogeneity when group error variances are unequal.

The test for regression slope homogeneity across groups (e.g., sex, race, and treatments) is used in such varied settings as the analysis of covariance, the study of aptitude by treatment interactions, and bias detection in differential prediction research. The accuracy of this test requires the seldom-considered assumption of equality of within-group error variances. This research studies the effect of violating that assumption on the power of the F test for regression slope equality and finds that the test may be substantially affected when sample sizes are equal and severely affected when sample sizes are unequal. Alternative procedures based on R. A. Alexander's (see record 1994-39680-001) normalized-t approximation, G. S. James's (1951) second-order approximation, the Welch-Aspin approximation, and the chi-square test are described and evaluated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A test of the context dependency of three causal models of halo rater error.

C. E. Lance et al (see record 1994-17452-001) tested 3 different causal models of halo rater error (general impression [GI], salient dimension [SD], and inadequate discrimination [ID] models) and found that the GI model better accounted for observed halo rating error than did the SD or ID models. It was also suggested that the type of halo rater error that occurs might vary as a function of rating context. The purpose of this study was to determine whether rating contexts could be manipulated that favored the operation of each of these 3 halo-error models. Results indicate, however, that GI halo error occurred in spite of experimental conditions designed specifically to induce other forms of halo rater error. This suggests that halo rater error is a unitary phenomenon that should be defined as the influence of a rater's general impression on ratings of specific ratee qualities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affective variables and school achievement: A study of possible causal influences.

Studied the predictive and causal relationship of affective variables and academic achievement (376 Ss in Grades 3–6), both concurrently and 1 yr later. Affective characteristics studied were general and academic self-concept, academic locus of control, and expectations for future academic achievement (Piers-Harris Children's Self-Concept Scale, Student's Perception of Ability Scale, Intellectual Achievement Responsibility Questionnaire, and the Projected Academic Performance Scale) whereas levels of achievement were ascertained by end-of-year grades. The findings indicate that affective variables, especially academic self-concept, made a small but significant contribution to school grades. The data suggest a possible reciprocal interaction between affective characteristics and school achievement. Implications for children experiencing learning difficulties are discussed. (French abstract) (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting group-level outcome variables from variables measured at the individual level: A latent variable multilevel model.

In multilevel modeling, one often distinguishes between macro-micro and micro-macro situations. In a macro-micro multilevel situation, a dependent variable measured at the lower level is predicted or explained by variables measured at that lower or a higher level. In a micro-macro multilevel situation, a dependent variable defined at the higher group level is predicted or explained on the basis of independent variables measured at the lower individual level. Up until now, multilevel methodology has mainly focused on macro-micro multilevel situations. In this article, a latent variable model is proposed for analyzing data from micro-macro situations. It is shown that regression analyses carried out at the aggregated level result in biased parameter estimates. A method that uses the best linear unbiased predictors of the group means is shown to yield unbiased estimates of the parameters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding L.O.V.E. (left out variables error): A method for estimating the effects of omitted variables.

Whenever nonexperimental methods are used to test a hypothesis and 1 or more predictor (independent) variables that may affect the criterion (dependent) variable are omitted from the analyses, it is possible that the estimates of the effects of the predictors are biased or that the omitted variable could account entirely for the effects attributed to one or more of the predictors. In this article, a technique is developed for determining when a variable omitted from a linear model can account for the effects attributed to a predictor included in that model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Propensity score techniques and the assessment of measured covariate balance to test causal associations in psychological research.

There is considerable interest in using propensity score (PS) statistical techniques to address questions of causal inference in psychological research. Many PS techniques exist, yet few guidelines are available to aid applied researchers in their understanding, use, and evaluation. In this study, the authors give an overview of available techniques for PS estimation and PS application. They also provide a way to help compare PS techniques, using the resulting measured covariate balance as the criterion for selecting between techniques. The empirical example for this study involves the potential causal relationship linking early-onset cannabis problems and subsequent negative mental health outcomes and uses data from a prospective cohort study. PS techniques are described and evaluated on the basis of their ability to balance the distributions of measured potentially confounding covariates for individuals with and without early-onset cannabis problems. This article identifies the PS techniques that yield good statistical balance of the chosen measured covariates within the context of this particular research question and cohort. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of the nonequivalent control group design when subjects are growing.

Many experimental programs aim to accelerate the growth of individuals on some dimension of interest. Typically, a group exposed to the program is compared with a control group. When it is feasible, random assignment of Ss to the program and control groups assures an unbiased comparison between treatments. Without randomization there may be important differences between groups, in terms of pretreatment characteristics and growth potential. In the nonequivalent control group design, pretest and posttest data on both groups are obtained. Statistical methods are used to adjust posttest comparisons, based mainly on pretest information. A variety of statistical techniques have been proposed, but there is much disagreement among methodologists as to which, if any, are adequate. This article examines the adequacy of these techniques, from an individual growth perspective. The performance of various commonly used methods is examined under alternative assumptions about the nature of growth. It is concluded that statistical adjustments are generally inadequate in the face of nonequivalent growth systems across treatment groups. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imprecision of the hemodialysis dose when measured directly from urea removal. Hemodialysis Study Group

BACKGROUND: The postdialysis blood urea nitrogen (BUN; Ct) is a pivotal parameter for assessing hemodialysis adequacy by conventional blood-side methods, but Ct is relatively unstable because of hemodialysis-induced disequilibrium. The uncertainty associated with this method is potentially reduced or eliminated by measuring urea removed on the dialysate side, a more direct approach that can determine adequacy from the fraction of urea removed and by substituting an estimate of the equilibrated postdialysis BUN (Ceq) for Ct. For a patient with a known urea volume (V), Ceq, the equilibrated Kt/V (eKt/V), and the solute removal index (SRI) can be calculated from the predialysis BUN (C0), total urea nitrogen removed (A), and V from simple mass balance calculations (dialysate/volume method). However, a theoretical error analysis showed that relatively small errors in A, C0, or V are magnified when SRI or eKt/V is calculated using this method, especially at higher eKt/V values (for example, if eKt/V = 1.4 per dialysis, a 7% dialysate collection error causes a 20% error in eKt/V). METHODS: During three to four baseline dialyses in each of 39 patients enrolled in the pilot phase of the HEMO Study, "A" was measured using an instrument that sampled dialysate frequently (Biostat), and V was calculated from A, C0, and Ceq (median CV for V = 5.6%). The mean V was then applied to the dialysate/volume method to estimate eKt/V and SRI during two to five subsequent dialyses per patient (comparison dialyses). The accuracy and precision of these estimates were assessed by comparing them with eKt/V and SRI derived from a direct measurement of Ceq drawn 30 minutes after dialysis (reference method), from mathematical curve-fitting of sequential dialysate urea concentrations (dialysate curve-fit method), and from another blood-side method that estimates eKt/V from single pool Kt/V and the fractional rate of solute removal (rate method): eKt/V = spKt/V - 0.6.K/V + 0.03. RESULTS: During 128 comparison dialyses, median absolute errors for calculated eKt/V compared with the reference method were 0.169, 0.061, and 0.071 for the dialysate/volume method, the rate method, and the dialysate curve-fitting method, respectively. The corresponding correlation coefficients were 0.47, 0.88, and 0.81. For SRI, median absolute errors were 0.044, 0.018, and 0.027, and the correlation coefficients were 0.54, 0.85, and 0.74 for the three methods. CONCLUSIONS: The precision of eKt/V and SRI measurements was significantly lower for the dialysate/volume method compared with the blood-side methods. Inclusion of the dialysate curve analysis provided by the Biostat restored precision to the dialysate method to a level comparable to that of the blood-side methods. New techniques employing dialysate urea analysis should include a concentration profile to avoid these inherent methodological errors and assure the accuracy of eKt/V and SRI.     

Comparison of fixation disparity curve variables measured with the Sheedy Disparometer and the Wesson Fixation Disparity Card

BACKGROUND: Previous studies suggest differences in the fixation disparity curves obtained with the Sheedy Disparometer and the Wesson Fixation Disparity Card, the two most commonly used methods for measuring fixation disparity. In one study the investigators proposed that the differences do not exist for subgroups divided by phoria. The purpose of this paper is to try to clarify this issue by use of two large sets of data. METHODS: Dissociated phorias were measured by the von Graefe method. Fixation disparity curves were plotted using the Disparometer and the Wesson card. RESULTS: Type I fixation disparity curves were most common with the Wesson card. Type II curves were found more often with the Disparometer than with the Wesson card. The x-intercepts were shifted in the base-in (BI) direction with the Wesson card compared to the Disparometer. The y-intercepts were shifted in the exo direction with the Wesson card compared to the Disparometer. The differences were statistically significant regardless of whether the dissociated phoria was exo or eso. The slope of the fixation disparity curve was steeper with the Wesson card than with the Disparometer. The difference was statistically significant for exophores but not for esophores. The differences between results obtained with the two instruments are not consistent from one subject to another as shown by high standard deviations of the differences. CONCLUSIONS: The fixation disparity curves measured with these two instruments are different. Fixation disparity parameters obtained from one of these instruments cannot be used with normative findings from the other.     

Scrutinizing psychological tests: Measurement equivalence and equivalent relations with external variables are the central issues.

Uses the concepts of measurement equivalence and equivalence of relations with external variables to clarify the central issues in scrutinizing psychological tests and their fairness to ethnic and cultural minority groups. The basic ideas, results, and implications are described using these concepts. The criticisms of this article by P. Bobko and J. F. Kehoe (see record 1983-24733-001) are shown to be based on an incorrect premise. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marital conflicts in the home when children are present versus absent.

Characteristics of marital conflict when children (8-16 years) were present versus absent were compared on the basis of 47 mothers' and fathers' reports during a 15-day period. Mothers described 669 incidents of marital conflict, and fathers described 551 incidents. About two thirds of the conflicts occurred in children's absence. Contrary to predictions, conflicts in which children were present were more negative (e.g., more negative emotions, more destructive conflict tactics) and more often about children than were child-absent conflicts. Although parents may attempt to protect children from conflict exposure, children tend to be exposed to a relatively hostile and emotionally negative subset of the marital conflicts that occur in the home. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychometric evaluation of scales when their scoring keys are unavailable.

Some psychological and educational tests are scored only by service organizations or computer programs that provide no access to scoring keys. The degree to which the keys need to be publicly available to evaluate different kinds of reliability and validity is examined. It is concluded that if keys are not provided, it is essential that (a) the scoring service provide internal consistency reliabilities on each batch of scales scored and (b) samples of items that correlate well with the total scale be given in the manual if content validity is claimed. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The development of reasoning with causal conditionals.

A total of 512 children in Grades 1 through 6 received a conditional inference task using causal conditionals (If cause P, then effect Q) and a generation of alternatives task. The inference task used premises for which there were few or many possible alternative causes. Results show a steady age-related increase in uncertainty responses to the two uncertain logical forms, affirmation of consequent (AC) and denial of antecedent (DA), and an increase in production of disabling conditions for modus ponens. More uncertainty responses were produced to AC and DA with premises with many possible alternatives. Individual differences in inference production were related to numbers of alternatives produced in the generation task. Results support the idea that both developmental and individual differences in reasoning can be at least partially explained by differential access to knowledge stored in long-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality resemblances in adoptive families when the children are late-adolescent or adult.

Members of 220 families who had adopted children at least 14 yrs previously completed the California Psychological Inventory and Thurstone Temperament Schedule to investigate personality resemblances among adoptees and their adoptive families. Adopted children were in late adolescence or adulthood. Results show that, consistent with other recent adoption studies, there was little resemblance between parents and adopted children or between adopted and natural siblings. The presence of a biological relationship raised correlations slightly, suggesting that much of the explanation for personality variation lies in within-family environmental variation or nonadditive genetic effects. It is noted that, in previous research, young adopted children were better adjusted on the average than biological children in the same families; however, this was no longer true for the late adolescents and young adults of the present study. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Practice effect on the Minnesota Clerical Test when alternate forms are used.

"1. Repeated administrations of alternate forms of the Minnesota Clerical Test show less practice effect than repeated tests with identical forms. 2. The degree of practice effect is a 6.4% increase in mean score on the Numbers test, 6.5% in the Names test, when Forms A and B are administered in ABBA order. 3. The immediate development of alternate test forms of the Minnesota Clerical Test is contra-recommended in view of the substantial differences in test difficulty on the Numbers test. 4. Any attempt to develop alternate forms of the Minnesota Clerical Test for the Numbers test should be preceded by a basic study of test-content factors underlying inequalities in form difficulty." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clarifying problems and offering solutions for correlated error when assessing the validity of selected-subtest short forms.

The correlation between a short-form (SF) test and its full-scale (FS) counterpart is a mainstay in the evaluation of SF validity. However, in correcting for overlapping error variance in this measure, investigators have overattenuated the validity coefficient through an intuitive misapplication of P. Levy's (1967) formula. The authors of the present article clarify that such corrections should be based on subtest-level versus FS-level data. Additionally, the authors propose a simple, modified equation incorporating FS-level scores that provides liberal and conservative validity measures for comparison across estimation methods, and they demonstrate its use in both a normative (N = 2,450) and clinical psychiatric (N = 216) sample. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of dichotomous variables in the presence of serial dependence.

[Correction Notice: An erratum for this article was reported in Vol 98(3) of Psychological Bulletin (see record 2009-20912-001). An unnecessary σ was added to the second line of Equation 32 on page 555. The second line should read: + 1/???](1 + ?a?b)/(1 – ?a?b), with the rest of the equation correct as printed.] Presents a model for the analysis of dichotomous data generated under a Markov chain model. Methods for estimating, testing, and comparing proportions and for analyzing dyadic interactions are described and compared with the standard techniques derived under the assumption of serial independence. It is shown that the regular test statistics must be adjusted by a correction factor that is a simple function of the within-S serial dependence parameter. Eigenvalues of the transition matrix are appended. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Three-dimensional reconstruction of curves from pairs of projection views in the presence of error. II. Analysis of error

We have previously described an approach to 3D intracerebral vascular reconstruction that uses an MRA as a reconstruction base. Additional vessels seen only by angiography are added by segmenting 2D curves from projection angiograms and reconstructing these curves into 3D, building upon the MRA. This paper is the second of two that discuss the specific problem of reconstructing a 3D curve from a given pair of 2D curves in the presence of error. The method presented is capable of detecting and handling many errors produced by misregistration, image distortion, or misdefinition of 2D curves. The first paper gives an algorithm. The current paper discusses factors affecting the accuracy of a reconstructed curve, with emphasis upon registration error. We analyze the spatial accuracy of a reconstructed point in terms of the relationships between pixel size, relative viewing angle, 3D point location, and registration error. We provide a theoretical framework that, given the known error properties of a registration algorithm, allows optimization of the viewing geometry so as to produce the highest precision of point reconstruction. A major focus is the effect of registration error upon the reconstruction of a curve. We subdivide registration error into two types, one of which produces smoothly continuous point placement errors and the other of which produces pixel pairing errors. We test our ability to reconstruct a 3D curve in the presence of both. Finally, we summarize approaches to other sources of error. We conclude with a list of recommendations to optimize reconstruction accuracy. When projection points are associated by the rules of epipolar geometry, viewplane point displacements should not exceed 1.5-2 mm along the axis perpendicular to epipolar planes.     

Summation of reinforcement rates when conditioned stimuli are presented in compound.

Three experiments used delay conditioning of magazine approach in rats to examine the summation of responding when two conditioned stimuli (CSs) are presented together as a compound. The duration of each CS varied randomly from trial-to-trial around a mean that differed between the CSs. This meant that the rats' response rate to each CS was systematically related to the reinforcement rate of that CS, but remained steady as time elapsed during the CS (Harris & Carpenter, 2011; Harris, Gharaei, & Pincham, 2011). When the rats were presented with a compound of two CSs that had been conditioned separately, they responded more during the compound than during either of the CSs individually. More significantly, however, in all three experiments, the rats responded to the compound at the same rate as they responded to a third CS that had been reinforced at a rate equal to the sum of the reinforcement rates of the two CSs in compound. We discuss the implications of this finding for associative models (e.g., Rescorla & Wagner, 1972) and rate-based models (Gallistel & Gibbon, 2000) of conditioning. (PsycINFO Database Record (c) 2011 APA, all rights reserved)