Multiple regression analysis is frequently being employed in experimental and non-experimental research. However, when data include predictor variables that are correlated, some regression results can become difficult to interpret. This paper presents a study to provide a demonstration that structure coefficients may be useful in these cases.…

If the quantitative result of a study is observed only when the mean difference is statistically significant, the observed mean difference, variance, and effect size are biased estimators of corresponding population parameters. The exact distribution of sample effect size and the maximum likelihood estimator of effect size are derived. (Author/BW)

The Welch-James procedure may be used to test hypothesis on means, when independent samples from populations with heterogenous variances are available. Summation formulas for the Welch-James procedure are presented for the 2x2 design. Matrix formulas that permit routine application of the procedure to crossed factorial designs are presented.…

This report compares findings from the End of Training surveys administered to Participant Teachers (PTs) who took part in the Classic version of Intel Teach to the Future and who took part in the Expansion version of Intel Teach to the Future. Classic survey data were collected between March 2001 and July 2003. PT Expansion survey data were…

This paper illustrates the use of the McNemar Test, using a hypothetical problem. The McNemar Test is a nonparametric statistical test that is a type of chi square test using dependent, rather than independent, samples to assess before-after designs in which each subject is used as his or her own control. Results of the McNemar test make it…

Given decades of lucid, blunt admonitions that statistical significance tests are often misused, and that the tests are somewhat limited in utility, what is needed is less repeated bashing of statistical tests, and some honest reflection regarding the etiology of researchers' denial and psychological resistance (sometimes unconscious) to improved…

The controversy about the use or misuse of statistical significance testing has become the major methodological issue in educational research. This special issue contains three articles that explore the controversy, three commentaries on these articles, an overall response, and three rejoinders by the first three authors. They are: (1)…

This article makes a plea for the greater use of non-parametric methods in introductory statistics courses. (MM)

See TM 500 270 in this issue. (CK)

Statistical significance is not a sufficient condition for claiming a hypothesis has been supported. Constructive replications are more important. Statistically significant results may be meaningless while a sequence of nonsignificant results may be quite important. Gives advice on how to overcome some limitations of classifical statistical…

Either Bartlett's chi-square test of sphericity or Steiger's chi-square test can be used to test the significance of a correlation matrix to determine the appropriateness of factor analysis. They were evaluated using computer-generated correlation matrices. Steiger's test is recommended due to its increased power and computational simplicity.…

Analysis of 230 major articles in the "Journal of Medical Education" shows 91 percent of those reporting medical education research had less than a 50-50 chance of detecting a small treatment effect. Similar low statistical power was found in other disciplines. Guidelines for reporting research are provided. (MSE)

Examines what power-related changes occured in science education research over the past decade as a result of an earlier survey. Previous recommendations are expanded/expounded upon within the context of more recent work in the area. Proposes guidelines for reporting minimal amount of information for clear/independent evaluation of research…

Suggests why statistical power is of special importance to English education researchers, specifies procedures for calculating power, and assesses the power of empirical research published in this journal during a three-year period. (FL)

A novel solution to the statistical problems in an evaluation of rare events is described. The significance of variations in the number of child homicides is analyzed in a binary time series of "active" months for monitoring future incidence and related systemic events. (Author/CM)