The Effects of Type I Error Rate and Power of the ANCOVA F Test and Selected Alternatives Under Nonnormality and Variance Heterogeneity

The authors sought to identify through Monte Carlo simulations those conditions for which analysis of covariance (ANCOVA) does not maintain adequate Type I error rates and power. The conditions that were manipulated included assumptions of normality and variance homogeneity, sample size, number of treatment groups, and strength of the covariate-dependent variable relationship. Alternative tests studied were Quade's procedure, Puri and Sen's solution, Burnett and Barr's rank difference scores, Conover and Iman's rank transformation test, Hettmansperger's procedure, and the Puri-Sen-Harwell-Serlin test. For balanced designs, the ANCOVA F test was robust and was often the most powerful test through all sample-size designs and distributional configurations. With unbalanced designs, with variance heterogeneity, and when the largest treatment-group variance was matched with the largest group sample size, the nonparametric alternatives generally outperformed the ANCOVA test. When sample size and variance ratio were inversely coupled, all tests became very liberal; no test maintained adequate control over Type I error.     

The Role of the Year Leader: an Analysis of the Perceptions of Year Leaders and Deputy Heads in 8‐12 Middle Schools

Today's school leaders are searching for a way to give value to and effectively manage a school's intangible assets to create a more holistic picture of student success. Schools establish partnerships with community organizations towards this end and to ultimately impact student learning. Utilizing the framework of principals as knowledge managers, this paper describes how school principals involved in a university partnership developed a tool to manage and intentionally utilize the intangible assets of the school–university partnership to increase student learning. Included are examples of how the tool was applied and suggestions for adapting the tool to any school partnership.     

Prolog programming techniques

In this paper we introduce the concept of a Prolog programming technique. This concept is then distinguished both from that of an algorithm and that of a programming cliché. We give examples and show how a knowledge of them can be useful in both programming environments and in teaching programming skills. The extraction of the various techniques is outlined. Finally, we discuss the problem of representing techniques where we conclude that the most promising approach is the development of a suitable meta-language.     

Multiple regression analysis of sib-pair data on reading to detect quantitative trait loci

A simple extension of the DeFries and Fulker multiple regression model for twin analysis is applied to the problem of detecting linkage in a quantitative trait. The method, employing sib pairs, is based on that of Haseman and Elston. Reading data from 19 extended pedigrees were analyzed employing RLFPs as markers on chromosome 15 and using the widely available statistical applications software package, SAS. A number of possible linkages were detected, indicating that this approach is both powerful and effective, especially in the case of selected samples. Detecting genotype-environment interaction and the issue of power are briefly discussed. The programs used are available upon request.     

A cross-national survey of cultural expectations and sex-role standards in reading

Cultural expectations and sex-role standards about reading in Canada, Denmark, England, Finland, Israel, Japan, and U.S.A. were investigated. A picture test showing various activities and objects including reading and books was administered in each country to six sub-samples that approximated to the levels: students in grades I, IV, VIII, and XII, college students, and adults. Subjects had to ascribe the activity or object as being appropriate for either a boy or a girl. The results were consistent with the hypothesis that cultural expectations and sex-role standards about reading are congruent within one country but that they differ between countries. In particular, boys in Canada and the U.S.A. rapidly learn to perceive reading as a feminine activity, whereas Danish and Japanese males at all ages consistently view reading as acceptable masculine behaviour.     

Maternal social support as a predictor of mother-child stress and stimulation

There is increasing interest in the role of social support in determining risk for child abuse and neglect. The present study assessed the relationship between maternal social support and two areas: stress in the mother-child relationship: and level of stimulation provided in the home. Maternal social support was assessed prenatally and at a two-year follow-up, while the latter variables were compiled at the two-year follow-up. The data were obtained from 38 urban, low SES (80% on public assistance) mothers and their 2-year-old children. Maternal social support correlated positively with level of stimulation and negatively with level of mother-child stress, and was the best predictor of both, relative to any SES, mother or child variables. In addition, high stress, low support mothers provided significantly less stimulation to their children. The theoretical implications for social support as a mediator variable as well as its implications for early identification and prevention efforts in abuse and neglect are discussed.