This study analyzes parent and professional organizations' effectiveness in national special education policy from 1975 to the present. Of specific interest are the relationships between groups' policy victories, how groups construct their political messages, and organizational characteristics. The research is significant in that it is one of the…

The present study uses a feminist theoretical framework to explore risk factors for the development of posttraumatic stress symptoms following intimate partner violence, with a community sample of 120 low-income European American and African American women. Hierarchical regression analyses were used to examine demographic, violence, and mental…

A method for comparing the cross-validated classification accuracies of predictive discriminant analysis and logistic regression classification models is presented under varying data conditions for the two-group classification problem. With this method, separate-group, as well as total-sample proportions of the correct classifications, can be…

An alternative is proposed for the Johnson-Neyman procedure (P. O. Johnson and J. Neyman, 1936). Used when heterogeneous regression lines for two groups are analyzed, the Johnson-Neyman procedure is a technique in which the difference between the two linear regression surfaces for the criterion variate (Y) is estimated conditional on a realization…

Many researchers are unfamiliar with suppressor variables and how they operate in multiple regression analyses. This paper describes the role suppressor variables play in a multiple regression model and provides practical examples that explain how they can change research results. A variable that when added as another predictor increases the total…

The relationship between the quantity of nonacademic achievements and personality test scores was investigated. The nonacademic score was derived from nine nonacademic achievement scales on the American College Test. The predictor variables consisted of 14 scale scores from the Omnibus Personality Inventory and one academic aptitude measure.…

This study was designed to: (1) assess the influence of an instructional set given to an observer regarding the presence or absence of a predictable pattern in the observed interaction, (2) extend and replicate findings of a previous study of observer accuracy, and (3) identify some of the specific types of errors made by observers in coding…

The purpose of this study was to determine which of six methods of ordering variables in a discriminant analysis yields subsets of variables that have the greatest discriminatory power. One method is based on univariate mean-square (or F) ratios, a second method on stepwise ordering, two methods on linear discriminant function (LDF) variable…

The E (for Euclidean) correlation coefficient is introduced as a general formulation of a variety of measures of association. Characteristics of the coefficient are discussed, and 23 measures of association are shown to be or not be E coefficients. (JKS)

Ridge regression is an approach to ameliorating the problem of large standard errors of regression estimates when predictor variables are highly intercorrelated. An interactive computer program is presented which allows for investigation of the effects of using various ridge regression adjustment values. (JKS)

This analysis of Zipf's law uses an index for the sequence of observed values of the variables in a Zipf-type relationship. Three important properties relating rank, count, and frequency are identified, shapes of Zipf-type curves are described, and parameters of the Mandelbrot-Zipf law are discussed. (Author/LRW)

Examined the power of seven demographic variables (sex, age, employment status, length of work experience, education, type of institution, and occupational level) to predict nursing-home staff empathy in interactions with residents. Results indicated only the variables in combination and work experience alone were significant. (Author/BL)

Maintains that simple squaring of the correlation coefficient between two variables to obtain "the degree to which the variance of one is explained by the other" is often misleading, represents "vulgarized knowledge," and obscures more meaningful relationships between variables. Illustrates this point with scatter-plot diagrams…

Examined individuals differing in sex, age, profession, eminence and fame, and historical period for presence of the birthday-deathday phenomenon. Found a decrease in probability of death with approaching birthday followed by an increase in most males. Females showed an initial rise in probability of death with approaching birthday, followed by a…

Tested two hypotheses relative to duration of marriage in 11,559 divorcing families in northern California. Confirmed that the presence of children is associated with longer marriage duration but not that the presence of children younger than age two was associated with longer marital duration. (NRB)