Equating "r"-based and "d"-based Effect Size Indices: Problems with a Commonly Recommended Formula.

Aaron, Bruce; Kromrey, Jeffrey D.; Ferron, John

Alert:

Limited Availability of Full-Text Documents. Click here for more information, or here to request the return of a PDF online.

Help

Tutorial

Help |

Tutorial

Help |

Tutorial

Help With This Page

Back to Search Results Help Permalink Share this record

More Info:
Help 0 items in My Clipboard | Add record to My Clipboard

Record Details - ED433353

Title: Equating "r"-based and "d"-based Effect Size Indices: Problems with a Commonly Recommended Formula.

Full-Text Availability Options:

ERIC Full Text (277K)

Related Items: Show Related Items

Click on any of the links below to perform a new search
Title:	Equating "r"-based and "d"-based Effect Size Indices: Problems with a Commonly Recommended Formula.
Authors:	Aaron, Bruce; Kromrey, Jeffrey D.; Ferron, John
Descriptors:	Correlation; Effect Size; Estimation (Mathematics); Meta Analysis; Sample Size
Source:	N/A
More Info: Help Peer Reviewed:
Publisher:	N/A
Publication Date:	1998-11-03
Pages:	13
Pub Types:	Reports - Research; Speeches/Meeting Papers
Abstract:	Two general categories comprise the various effect size indices that have been proposed for use in meta-analysis: (1) the "d"-type estimator (based on magnitude of mean difference); and (2) the "r"-type estimator (based on magnitude of correlation). In meta-analyses, researchers often must convert these effect size indices to a common metric to aggregate and synthesize results from various studies empirically. A commonly recommended formula for equating mean-difference effect sizes and correlational effect sizes was found to lead to inaccurate results, particularly with small sample sizes. A correct formula for converting "d"-based and "r"-based effect size indices is presented. Results of applying the common and corrected formulas are illustrated for a variety of data conditions at various sample sizes and effect sizes, suggesting that bias as large as 20 percent results from the common formula, something that can be avoided by applying the alternative equation. (Author/SLD)
Abstractor:	N/A
Reference Count:	N/A

Note:	Paper presented at the Annual Meeting of the Florida Educational Research Association (43rd, Orlando, FL, November 2-4, 1998).
Identifiers:	N/A
Record Type:	Non-Journal
Level:	1 - Available on microfiche
Institutions:	N/A
Sponsors:	N/A
ISBN:	N/A
ISSN:	N/A
Audiences:	N/A
Languages:	English
Education Level:	N/A

Back to Search Results