What causes the literacy gap and can schools compensate for it? The authors investigated 3 drivers of the gap: preliteracy knowledge, schooling, and the summer vacation. Longitudinal literacy data over 5 time points were collected on 126 five-year-olds attending higher or lower socioeconomic status (SES) schools during their first 15 months of…

The purpose of the present study was to investigate the statistical properties of two extensions of the Levin-Wampold (1999) single-case simultaneous start-point model's comparative effectiveness randomization test. The two extensions were (a) adapting the test to situations where there are more than two different intervention conditions and (b)…

In 3 experiments, undergraduates used their own best method (control) or an "imposed" face-name mnemonic strategy to associate 18 caricatured faces, names, and additional facts. On all immediate tests (prompted by the faces), and on the delayed tests of Experiments 2a and 2b combined, mnemonic students statistically outperformed control students…

Supports a two-step approach to the estimation and discussion of effect sizes, making a distinction between single-study decision-oriented research and multiple-study synthesis. Introduces and illustrates the concept of "conclusion coherence." (Author/SLD)

Outlines concerns that must be addressed by those who advocate replacing statistical hypothesis-testing with alternative data-analysis strategies. Suggests that commonly recommended alternatives are not perfect and that various hypothesis-testing modifications can be implemented to make the process and its conclusions more credible. Hypothesis…

Regions of significance in aptitude-by-treatment-interaction studies are examined by the traditional statistical approach and an alternative approach which integrates: (1) testing for the parallelism of two or more regression lines; (2) testing for their identity; and (3) Scheffe's theorem. (Author/RL)

Proposes modifications to the recent suggestions by B. Thompson (1996) for an American Educational Research Association editorial policy on statistical significance testing. Points out that, although it is useful to include effect sizes, they can be misinterpreted, and argues, as does Thompson, for greater attention to replication in educational…

In three experiments, the authors investigated whether statistical language influences readers' interpretations of research results. Although the authors argue that "significant" language changes should not be mandated for quantitative research studies in scientific journals, if such changes are mandated, then use of the term "statistical" is…

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…

Because of criticisms leveled at statistical hypothesis testing, some researchers have argued that measures of effect size should replace the significance-testing practice. We contend that although effect-size measures have logical appeal, they are also associated with a number of limitations that may result in problematic interpretations of them…

Journal editors respond to criticisms of reliance on statistical significance in research reporting. Joel R. Levin ("Journal of Educational Psychology") defends its use, whereas William D. Schafer ("Measurement and Evaluation in Counseling and Development") emphasizes the distinction between statistically significant and important. William Asher…