After reviewing the multiple fit indices in structural equation models, evidence on their behavior is presented through simulation studies in which sample size, estimation method, and model misspecification varied. Two sampling studies, with and without known populations, are presented, and implications for the use of fit indices are discussed.…

Effectiveness of jackknife methods in reducing bias in estimation of the log-1 autocorrelation parameter p1 was evaluated through a Monte Carlo study using sample sizes ranging from 6 to 500. These estimates appear less biased in the small sample case than many that have been investigated recently. (SLD)

A variation of the Mantel Haenszel procedure is proposed that improves detection rates of nonuniform differential item functioning (DIF) without increasing the Type I error rate. The procedure, which is illustrated with simulated examinee responses, involves splitting the sample into low- and high-performing groups. (SLD)

Maximized correlation as an internal reliability estimate for tests with few items was investigated. An actual sampling distribution of maximum correlation--"r" max--was empirically derived from 100 samples of 50 cases each from Rorschach test data and compared with those of alpha and an odd/even split, using 2,020 Rorschach protocols.…

Proposes a two-stage estimation method for the analysis of covariance structure models with ordinal ipsative data (OID). A goodness-of-fit statistic is given for testing the hypothesized covariance structure matrix, and simulation results show that the method works well with a large sample. (SLD)

Presents formulas for estimating sample sizes to provide specified levels of power for tests of significance from a longitudinal design allowing for subject attrition. These formulas are derived for a comparison of two groups in terms of single degree-of-freedom contrasts of population means across the study timepoints. (Author/SLD)

This research is an empirical study, through Monte Carlo simulation, of the effects of violations of the assumptions for the oneway fixed-effects analysis of variance (ANOVA) and analysis of covariance (ANCOVA). Research reaffirms findings of previous studies that suggest that ANOVA and ANCOVA be avoided when group sizes are not equal. (SLD)

The behavior of eight measures of fit used to evaluate confirmatory factor analysis models was studied through Monte Carlo simulation to determine the extent to which sample size, model size, estimation procedure, and level of nonnormality affect fit when analyzing polytomous data. Implications of results for evaluating fit are discussed. (SLD)

Type I error rates for the Johansen test were estimated using simulated data for a variety of conditions. Results indicate that Type I error rates for the Johansen test depend heavily on the number of groups and the ratio of the smallest sample size to the number of dependent variables. Sample size guidelines are presented. (SLD)

Examined the effects of sample size and other design features on correspondence between factors obtained from analysis of sample data and those present in the population from which the samples were drawn, examining these phenomena in the situation in which the common factor model does not hold exactly in the population. Tested a theoretical…

Describes the use of critical multiplism to evaluate the advantages and disadvantages of random sampling and deliberate sampling for heterogeneity. Suggests a model for using deliberate sampling for heterogeneity when the population parameters are unknown. Applies this model to a study of the psychosocial rehabilitation workforce. (SLD)

Studied the effects of sample size on the cumulative distribution of selected fit indices using Monte Carlo simulation. Generally, the comparative fit index exhibited very stable patterns and was less influenced by sample size or data types than were other fit indices. (SLD)

Describes and compares useful and unified power formulas for analysis of covariance and change-score analyses, indicating the implications of each for sample size requirements. Contains practical recommendations for evaluations and outlines a simple spreadsheet approach. (SLD)

Health care and educational trials face similar methodological challenges. Methodological reviews of health care trials have shown that a significant proportion have methodological flaws. Whether or not educational trials have a similar proportion of poor-quality trials is unknown. The authors undertook a methodological comparison between health…

Group-level parametric and non-parametric item response theory models were applied to the Consumer Assessment of Healthcare Providers and Systems (CAHPS[R]) 2.0 core items in a sample of 35,572 Medicaid recipients nested within 131 health plans. Results indicated that CAHPS responses are dominated by within health plan variation, and only weakly…