Develops a testing procedure based on a model including treatment effects on residual variances. (Author/RC)

Among the many problems faced by family researchers in conducting experimental research in field settings is that posed by nonequivalent and intact treatment and control groups. Nonequivalence refers to the assignment of individuals to treatments on a nonrandom basis, thus generating treatment groups with different expected values on one or more…

Exploratory research with large numbers of variables and even larger numbers of relationships is likely to result in frequent Type II errors; that is falsely accepting an incorrect null hypotheses. There are three ways of reducing Type II errors: (1) choosing a lower significance level, which then increases the probability of Type I error; (2)…

Three procedures used to control Type I error rate in stepwise regression analysis are forward selection, backward elimination, and true stepwise. In the forward selection method, a model of the dependent variable is formed by choosing the single best predictor; then the second predictor which makes the strongest contribution to the prediction of…

A linear classification rule (used with equal covariance matrices) was contrasted with a quadratic rule (used with unequal covariance matrices) for accuracy of internal and external classification. The comparisons were made for seven situations which resulted from combining three data conditions (equal and unequal covariance matrices, minimal and…

The use of characteristic coding (dummy coding) is made in showing solutions to four multivariate problems using canonical analysis. The canonical variates can be themselves analyzed by the use of multiple linear regression. When the canonical variates are used as criteria in a multiple linear regression, the R2 values are equal to 0, where 0 is…

The work reported here is based on the second Malta National Literacy Survey, carried out in March 2002. All Year 5 pupils in Malta were involved and their literacy attainment in both Maltese and English was tested. Two parallel multi-level analyses were carried out, one for Maltese, the other for English. The background variables were; gender,…

First Amendment principles are fragile, unless they have widespread public support. People form lasting views about civil liberties and other political issues in adolescence. They are influenced by many factors, including what they learn and experience in schools. Therefore, schools' treatment of the Constitution and the press is important for the…

Magnitude of effect measures (MEMs), when adequately understood and correctly used, are important aids for researchers who do not want to rely solely on tests of statistical significance in substantive result interpretation. The MEM tells how much of the dependent variable can be controlled, predicted, or explained by the independent variables.…

A general procedure is presented for generating code values for a qualitative variable in multiple linear regression analyses that result in directly interpretable estimates of interest. The basic approach, in viewing ANOVA as a multiple regression problem, is to derive quantitative code values for the various levels of the qualitative ANOVA…

In their 2004 paper "The role of Advanced Placement and honors courses in college admissions," (see ED492533) Saul Geiser and Veronica Santelices of the University of California, Berkeley, addressed the use of Advanced Placement Program (AP) and honors courses as a criterion for admission at the University of California system and…

Using data from the final two rounds of the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), a longitudinal study begun in 2001, this First Look provides a snapshot of the demographic characteristics, reading and mathematics knowledge, fine motor skills, school characteristics, and before- and after-school care arrangements of the cohort…

Researchers should investigate statistical models that can help counselors decide how to treat individual clients. This research investigated the questions, "Given an effect size (ES) from a counseling outcome study, what is the probability that a client would have a negative response to the treatment, and what is the probability that the client…

In this paper the bootstrap technique was applied to the evaluation of potential predictive bias for different ethnic groups using the Scholastic Aptitude Test (SAT) and high school ranks to predict college grade point averages (GPAs). Data of three ethnic groups were used; the total number of subjects was close to 5,000. Both conventional…