This "What Works Clearinghouse Procedures and Standards Handbook (Version 3.0)" provides a detailed description of the standards and procedures of the What Works Clearinghouse (WWC). The remaining chapters of this Handbook are organized to take the reader through the basic steps that the WWC uses to develop a review protocol, identify…

This paper offers a practical guide to use null hypotheses significance testing and its alternatives. The focus is on improving the quality of statistical inference in quantitative communication research. More consistent reporting of descriptive statistics, estimates of effect size, confidence intervals around effect sizes, and increasing the…

Analyzed 150 articles from the "Journal of Applied Psychology" (JAP) from 1940 to 1999 to determine statistical reporting practices related to null hypothesis significance testing, American Psychological Association guidelines, and reform recommendations. Findings show little evidence that decades of cogent criticisms by reformers have…

This paper addresses the state of the art regarding the use of statistical significance tests (SSTs). How social science research will be conducted in the future is impacted directly by current debates regarding hypothesis testing. This paper: (1) briefly explicates the current debate on hypothesis testing; (2) reviews the newly published report…

Significance tests are often used inappropriately in counseling research. In addition to comments on the significance test controversy (Vacha-Haase and Nilsson, this issue), a wider historical context and personal experiences are provided. The controversy is discussed, and seven recommendations for using significance tests are included. (EMK)

Introduces the three subsequent articles from this special section, which extend the discussion of future prospects for progress in the reporting and interpreting of effect sizes by researchers. The authors of these pieces represent diverse views. (SLD)

Makes the case that science is best served when researchers focus on the size of effects and their practical significance. Advocates the use of confidence intervals for deciding whether chance or sampling variability is an unlikely explanation for an observed effect. Calls for more emphasis on effect sizes in the next edition of the American…

Statistical significance reporting and use in educational and psychological research is reviewed. An assessment of the use of statistical significance in articles published in MECD from 1990-1996 is presented. The elements of statistical significance (including sample size, effect size, and power), interpretation of results, common erroneous…

Researchers, journal editors, textbook authors, and those responsible for writing publication manuals must work together to enhance the thoughtful reporting of statistical results and to make clear the necessity for reporting effect sizes. (SLD)

Suggests that researchers should report the results of appropriate significance tests and the effect sizes associated with each test. Discusses the roles of textbook authors, publication manuals, and journal editors in leading the movement to better statistical reporting. (SLD)

The use of tests of statistical significance was explored, first by reviewing some criticisms of contemporary practice in the use of statistical tests as reflected in a series of articles in the "American Psychologist" and in the appointment of a "Task Force on Statistical Inference" by the American Psychological Association…