Effect size guidelines for individual differences researchers (Gignac and Szodorai, 2016)

This home study course entails the independent study of "Effect size guidelines for individual differences researchers" (Gignac and Szodorai, 2016), followed by the completion of a multiple-choice test on-line. Participants who receive a passing grade of 75% or higher on the test will receive 1 CE credit. In accordance with guidance from the APA CE office, we are limiting the number of chances to take the test to 2 times. Participants who fail the test may retake the test once at no additional charge, and receive CE credit if they do pass.

A copy of the journal article for this course is available at the ResearchGate website.

Upon completion of this home study program, the participant will be able to:

1. Describe the methodology employed in this study.
2. Describe how the study’s methodology differs from that of Hemphill (2003).
3. Describe how the study’s methodology differs from that of Cohen (1988).
4. List the effect size magnitudes recommended to interpret the size of uncorrected and corrected Pearson correlations.

This CE program is intended for psychologists who hold a doctoral degree. The course may be taken by other interested professionals (e.g.,senior human resource executives and consultants; upper-level managers).

The fee for this home-study program is $10, which is $10 per CE credit. The fee is fully refundable for 60 days or until the post-test is taken, whichever comes first.

A copy of the journal article for this course is available at the ResearchGate website.

The author of the journal article you will read for this home-study course is Dr. Gilles Gignac. Dr. Gignac is a professor of psychology at The University of Western Australia in Crawley Australia.

Publication citation:

Gignac and Szodorai (2016). Effect size guidelines for individual differences researchers. Personality and Individual Differences 102 (2016) 74–78. Retrieved June, 2018, from https://www.researchgate.net/profile/Gilles_Gignac/publication/305699288_Effect_size_guidelines_for_individual_differences_researchers/links/5a35034345851532e82da919/Effect-size-guidelines-for-individual-differences-researchers.pdf.

Article abstract:

Individual differences researchers very commonly report Pearson correlations between their variables of interest. Cohen (1988) provided guidelines for the purposes of interpreting the magnitude of a correlation, as well as estimating power. Specifically, r=0.10, r=0.30, and r=0.50 were recommended to be considered small, medium, and large in magnitude, respectively. However, Cohen's effect size guidelineswere based principally upon an essentially qualitative impression, rather than a systematic, quantitative analysis of data. Consequently, the purpose of this investigationwas to develop a large sample of previously published meta-analytically derived correlations which would allow for an evaluation of Cohen's guidelines from an empirical perspective. Based on 708 meta-analytically derived correlations, the 25th, 50th, and 75th percentiles corresponded to correlations of 0.11, 0.19, and 0.29, respectively. Based on the results, it is suggested that Cohen's correlation guidelines are too exigent, as b3% of correlations in the literature were found to be as large as r = 0.50. Consequently, in the absence of any other information, individual differences researchers are recommended to consider correlations of 0.10, 0.20, and 0.30 as relatively small, typical, and relatively large, in the context of a power analysis, as well as the interpretation of statistical results from a normative perspective.

APR Testing Services (APR) has no known conflict of interest with respect to this CE program. APR has not received any commercial support for this CE program.