Delineates and explains essential characteristics of single-case research methodology applied within domain of psychotherapy research. Presents single-case research as subclass of intrasubject research in which aggregation across subjects is avoided and generality of one's findings is addressed through replication on case-by-case basis.…

A simulation study compared the performance of the Mann-Whitney "U" test, Student's "t" test, and the alternate (separate variance) "t" test for two mutually independent random samples from normal distributions, with both one-tailed and two-tailed alternatives. Type I error probabilities were computed with equal and…

Why methodologists encourage the use of magnitude-of-effect (ME) indices as research interpretation aids is discussed, and different types of ME estimates are reviewed. Correction formulas developed to alternate statistical bias in ME estimates are also discussed, and their effects are illustrated. (SLD)

Three criticisms of conventional uses of structural significance testing are elaborated; and alternatives for augmenting statistical significance tests are reviewed, which include emphasizing effect size, evaluating statistical significance in a sample size context, and evaluating result replicability. Among ways of estimating result…

Describes the MINISIZE 2 computer program, which permits the user to determine the effect size and the minimum sample size needed so that results of a given analysis will be statistically significant. Explains the program's operation and provides examples. (SLD)

Sample sizes (n=15, 25, 50, 100) were examined (1,000 times each) with replacement from each of 5 data files from teacher subject test areas to compare statistical bias and standard error. Trivial levels of equating bias were present with small samples, and substantial increases in standard errors were found as the sample size decreased. (MAK)

Presents an experiment on the sampling process including sample size and particle size. (YDS)

This article considers the problem of power and sample size calculations for normal outcomes within the framework of multivariate linear models. The emphasis is placed on the practical situation that not only the values of response variables for each subject are just available after the observations are made, but also the levels of explanatory…

The demonstration of sample segregation, which is simple, and visually compelling illustrates the importance of sample handling for students studying analytical chemistry and environmental chemistry. The mixture used in this demonstration has two components, which have big particle size, and different colors, which makes the segregation graphic.

Kelley compared three methods for setting a confidence interval (CI) around Cohen's standardized mean difference statistic: the noncentral-"t"-based, percentile (PERC) bootstrap, and biased-corrected and accelerated (BCA) bootstrap methods under three conditions of nonnormality, eight cases of sample size, and six cases of population…

Confidence intervals (CIs) give information about replication, but many researchers have misconceptions about this information. One problem is that the percentage of future replication means captured by a particular CI varies markedly, depending on where in relation to the population mean that CI falls. The authors investigated the distribution of…

This study is a partial replication of L. Hu and P. M. Bentler's (1999) fit criteria work. The purpose of this study was twofold: (a) to determine whether cut-off values vary according to which model is the true population model for a dataset and (b) to identify which of 13 fit indexes behave optimally by retaining all of the correct models while…

Through Monte Carlo simulation, small sample methods for evaluating overall data-model fit in structural equation modeling were explored. Type I error behavior and power were examined using maximum likelihood (ML), Satorra-Bentler scaled and adjusted (SB; Satorra & Bentler, 1988, 1994), residual-based (Browne, 1984), and asymptotically…

The main objective of this article is to investigate the empirical performances of the Bayesian approach in analyzing structural equation models with small sample sizes. The traditional maximum likelihood (ML) is also included for comparison. In the context of a confirmatory factor analysis model and a structural equation model, simulation studies…

Homework assignments have been studied extensively in psychotherapy research, but there is little data on the way in which homework is transferred to clinical practice. A survey was conducted of 827 practicing psychologists nationwide regarding their use and attitudes toward homework. Overall, 68% of the present sample indicated that they "often"…