The biases and mean squared errors of the sample squared multiple correlation coefficient and five adjusted estimators of the population squared multiple correlation are examined. A quadratic estimator and the minimum variance unbiased estimator are also examined. These estimators are compared in terms of absolute bias and mean squared error.…

When the same parameters are estimated by data from several independent samples, it may happen that, for any pair of samples, even though the test for parameter discrepancy is statistically significant, the two individual confidence intervals overlap. To overcome this potential contradiction, a new type of one-sample confidence intervals is…

Three procedures for evaluating the sampling specificity of results are reviewed. These procedures are Tukey's jacknife technique, Efron's bootstrap technique, and cross-validation methods. The jacknife technique uses different subsamples derived from the original total data set to provide empirical estimates of the generalizability of effect…

Two estimators of effect size that are based on the sample quartiles are proposed and studied. One is for the situation where a treatment effect is evaluated against a control group, and the other is for a situation in which two parallel treatments are compared. Both are illustrated and evaluated. (SLD)

This study examines the magnitude of the difference between estimates from the 1990-91 Schools and Staffing Survey (SASS) using a Common Core of Data (CCD) definition of a school and a Quality Education Data (QED) definition of a school. The 1990-91 SASS sample design allows for the development of school and administrator estimates using either…

A generalized variance criterion is proposed to measure efficiency in item-response-theory (IRT) models. Heuristic arguments are given to formulate the efficiency of a design in terms of an asymptotic generalized variance criterion. Efficiencies of designs for one-, two-, and three-parameter models are compared. (SLD)

The purpose of this study was to develop a single procedure for comparing population variances which could be used for distribution forms. Bootstrap methodology was used to estimate the variability of the sample variance statistic when the population distribution was normal, platykurtic and leptokurtic. The data for the study were generated and…

The National Household Education Survey (NHES) is a data collection system of the National Center for Education Statistics that is designed to provide information on educational issues that can best be studied through contacting households rather than educational institutions. This report compares the information collected through telephone…

Empirical comparisons are made of three statistical sampling methods evaluated for estimating total number of relevant documents in collection for given query: simple random sampling, random sampling which assigns unequal selection probabilities to individual documents in collection, and curve fitting and extrapolation. Nine references and…

The effectiveness of five methods used to estimate the population parameters of a variable of interest from a random sample in the presence of non-response to mail surveys was tested in conditions that vary the return rate and the relationship of the variable of interest to the likelihood of response. Data from 125,092 adult Alabama residents in…

Effect sizes have been increasingly emphasized in research as more researchers have recognized that: (1) all parametric analyses (t-tests, analyses of variance, etc.) are correlational; (2) effect sizes have played an important role in meta-analytic work; and (3) statistical significance testing is limited in its capacity to inform scientific…

A study explored which nonexperimental comparison group methods provide the most accurate estimates of the impacts of mandatory welfare-to-work programs and whether the best methods work well enough to substitute for random assignment experiments. Findings were compared for nonexperimental comparison groups and statistical adjustment procedures…