This teaching supplement from the U.S. Census Bureau is designed for educators in grades 5 through 12. The Bureau offers it as a way of addressing the needs and concerns of teachers as they attempt to include statistical information about the everyday world in an effort to meet new educational standards. The supplement is presented in order to…

The normal curve has long been important in statistics. Most interval variables yield normal or quasi-normal distributions when data are collected from large samples, and the normal "Z" distribution is also used as a test statistic (e.g., to test differences between two means when sample size is large, since "t" approaches…

This research attempted to replicate and extend results from a previous study examining the effects on achievement of generating summaries or analogies while reading a lengthy text. Before the study, 111 undergraduate students from a large midwestern university were classified as high or low ability and randomly assigned to paired or individual…

New multivariate permutation tests are proposed that may be effectively substituted for Hotelling's T-Square test in situations commonly arising in educational research. The new tests: (1) are distribution-free; (2) provide tests of directional as well as non-directional hypotheses; (3) may be tailored for sensitivity to specific treatment…

Few methods have been tried and used to graphically represent more than two variables. This poster session showed a new method for representing three continuous variables on a single scatterplot using the THREEDE computer program. Two variables are represented as a normal bivariate distribution. The third variable is represented by a symbol, e.g.…

Statistical methods are presented for studying "correlates of diversity," defined as characteristics of educational organizations that predict dispersion on the dependent variable. Strategies based on exact distribution theory and asymptotic normal approximation are considered. (TJH)

Current practice in structural modeling of variables is limited to means and covariances based on multivariate normality assumptions. This article extends structural equation models to higher order product moments and to non-normal distributions. Areas of possible research are described. (Author/JKS)

A step-by-step outline is presented for testing the applicability of Lotka's law of scientific productivity. Steps include the computation of the values of the exponent and constant based on Lotka's method and the test for significance of observed frequency distribution against the estimated theoretical distribution derived from Lotka's formula.…

A Bayesian procedure is developed for the estimation of parameters in the two-parameter logistic item response model. Joint modal estimates of the parameters are obtained and procedures for the specification of prior information are described. (Author/LMO)

A recent study (Blair and Higgins, 1980) indicated a power advantage for the Wilcoxon W Test over student's t-test when calculated from a common mixed-normal sample. Results of the present study indicate that the t-test corrected for outliers shows a superior power curve to the Wilcoxon W.

A procedure for the analysis of judgmental estimates is derived. It uses a t-distribution concept to derive the relative experience of an expert and uses the derived experience as weight to obtain a weighted mean. Using this method, error in estimation was reduced by an average of one-half. (Author/BW)

The regression-discontinuity design (RDD) offers the possibility of making inferences about causal effects from observations on selected groups. Data from such a design are considered to have a truncated bivariate distribution. For the RDD, maximum likelihood parameter estimation procedures and tests of hypotheses are presented. (Author/BW)

Various federal agencies and the courts are facing questions about the legality and potential discrimination in sex-segregated mortality tables and discrepancies in retirement and insurance benefits. By using unisex mortality tables, TIAA-CREF is an unwilling pioneer in the insurance industry, but the tables' ultimate form remains in question.…

To clarify the findings of R. Gillett (1991) about the inequality of the means of test scores of minority and majority examinees, the standard errors of the quota-selected sample means and the sampling distribution of these means were studied through Monte Carlo simulation. Results explain that the quota selection inequality results from…

Distributions of psychiatric classifications among 42,479 persons with mental retardation were reviewed to determine relative rates of disorders for persons with both mental retardation and mental disorder. Analyses indicated that rates of reported schizophrenic and psychotic disorders were generally higher than expected relative to rates of other…