Purpose: The purpose of this study was to investigate the characteristics of missing physical activity (PA) data of children and youth. Method: PA data from the Chinese City Children and Youth Physical Activity Study ("N" = 2,758; 1,438 boys and 1,320 girls; aged 9-17 years old) were used for the study. After the data were sorted by the…

In May of 2011, the "Los Angeles Times" published, for the second time, results of statistical studies examining the variation in teacher and school performance in the Los Angeles Unified School District, based on the California Standards Tests for math and English Language Arts (ELA). The studies use data from the seven academic years…

This paper presents key new developments in the THES - QS World University Rankings in 2007, related to enhancements to the "Peer Review", "Data Collection" and "Statistical Aggregation" utilised in this ranking as well as discussing the decision to utilise Full-Time Equivalent (FTE) figures for personnel statistics. Indicator correlation is also…

The paper reflects on the use by the UK central government of statistical evidence in educational policy matters. Particular attention is given to school league tables. The paper is generally critical of government attitudes, but suggests that progress towards rational decision-making does occur. (Contains 5 notes.)

Discusses the inconsistent and shifting ways in which the U.S. Census treats race, color, and ethnicity. Suggests that long-term conceptual frameworks be developed so that the next census will not produce uneven categories based on unequal assumptions. (EVL)

A methodology is proposed to optimize the training classification performance of any suboptimal model. The method, referred to as univariate optimal discriminant analysis (UniODA), is illustrated through application to a two-group logistic regression analysis with 12 empirical examples. Maximizing percentage accuracy in classification is…

The technique of generalizing sample results in a classification study to large subpopulations of unequal sizes was examined. The usual output from the discriminant analysis routine in the Statistical Package for the Social Sciences was extended to handle the present statistical problems. Advantages of the technique were discussed. (Author/DWH)

Three methods of transforming unordered categorical response variables are described: (1) analysis using dummy variables; (2) eigenanalysis of frequency patterns scaled relative to within-groups variance; (3) categorical variables analyzed separately with scale values generated so that the grouping variable and the categorical variable are…

A model is presented for multiple pairwise comparisons of selected categories (cells) of a contingency table after the chi-square test has rejected the null hypothesis of equality of population proportions. The model determines which, if any, pairwise proportions have led to the rejection. (SLD)

A method for comparing the cross validated classification accuracies of linear and quadratic classification rules is presented under varying data conditions for the k-group classification problem. With this method, separate-group as well as total-group proportions of correct classifications can be compared for the two rules. McNemar's test for…

Press coverage of a suburban midwest school district is analyzed as a set of time series of observations including the amount and quality of coverage. Possible shifts in these series because of the emergence of controversial issues are analyzed statistically using the Integrated Moving Average Time Series Model. Evidence of significant shifts in…

Formulas for estimating cross-validated hit-rates, the number of correct classifications into an a priori grouping structure, were examined. The following mathematical formulas were compared: McLachlan's formula estimator, two Snappin and Knoke smoothed formula estimators, and the analytic leave-one-out estimator. The R method was included as a…

Three estimates of the probabilities of correct classification in predictive discriminant analysis were computed using mathematical formulas, resubstitution, and external analyses: (1) optimal hit rate; (2) actual hit rate; and (3) expected actual hit rate. Methods were compared using Monte Carlo sampling from two data sets. (Author/GDC)

Comparisons of the Wilcoxon test, Friedman test, and repeated-measures analysis of variance (ANOVA) on ranks in a computer simulation show that the Friedman test performs like the sign test whereas the ANOVA performs like the Wilcoxon test. Classification of these tests in introductory statistics textbooks should be revised. (SLD)

The nature of the criterion (dependent) variable may play a useful role in structuring a list of classification/prediction problems. Such criteria are continuous in nature, binary dichotomous, or multichotomous. In this paper, discussion is limited to the continuous normally distributed criterion scenarios. For both cases, it is assumed that the…