Demystifying omega squared: Practical guidance for effect size in common analysis of variance designs.

IF 7.6 1区心理学 Q1 PSYCHOLOGY, MULTIDISCIPLINARY

Psychological methods Pub Date : 2023-07-10 DOI:10.1037/met0000581.supp

Antoinette D A Kroes, Jason R. Finley

{"title":"Demystifying omega squared: Practical guidance for effect size in common analysis of variance designs.","authors":"Antoinette D A Kroes, Jason R. Finley","doi":"10.1037/met0000581.supp","DOIUrl":null,"url":null,"abstract":"Omega squared (ω^2) is a measure of effect size for analysis of variance (ANOVA) designs. It is less biased than eta squared, but reported less often. This is in part due to lack of clear guidance on how to calculate it. In this paper, we discuss the logic behind effect size measures, the problem with eta squared, the history of omega squared, and why it has been underused. We then provide a user-friendly guide to omega squared and partial omega squared for ANOVA designs with fixed factors, including one-way, two-way, and three-way designs, using within-subjects factors and/or between-subjects factors. We show how to calculate omega squared using output from SPSS. We provide information on the calculation of confidence intervals. We examine the problems of nonadditivity, and intrinsic versus extrinsic factors. We argue that statistical package developers could play an important role in making the calculation of omega squared easier. Finally, we recommend that researchers report the formulas used in calculating effect sizes, include confidence intervals if possible, and include ANOVA tables in the online supplemental materials of their work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).","PeriodicalId":20782,"journal":{"name":"Psychological methods","volume":" ","pages":""},"PeriodicalIF":7.6000,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Psychological methods","FirstCategoryId":"102","ListUrlMain":"https://doi.org/10.1037/met0000581.supp","RegionNum":1,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PSYCHOLOGY, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 1

Abstract

Omega squared (ω^2) is a measure of effect size for analysis of variance (ANOVA) designs. It is less biased than eta squared, but reported less often. This is in part due to lack of clear guidance on how to calculate it. In this paper, we discuss the logic behind effect size measures, the problem with eta squared, the history of omega squared, and why it has been underused. We then provide a user-friendly guide to omega squared and partial omega squared for ANOVA designs with fixed factors, including one-way, two-way, and three-way designs, using within-subjects factors and/or between-subjects factors. We show how to calculate omega squared using output from SPSS. We provide information on the calculation of confidence intervals. We examine the problems of nonadditivity, and intrinsic versus extrinsic factors. We argue that statistical package developers could play an important role in making the calculation of omega squared easier. Finally, we recommend that researchers report the formulas used in calculating effect sizes, include confidence intervals if possible, and include ANOVA tables in the online supplemental materials of their work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

查看原文本刊更多论文

揭开欧米茄平方的神秘面纱:方差设计中常见分析效应大小的实用指南。

Omega平方（ω^2）是方差分析（ANOVA）设计的效应大小的度量。它的偏差小于eta平方，但报告的频率较低。这在一定程度上是由于缺乏关于如何计算它的明确指导。在本文中，我们讨论了效应大小度量背后的逻辑、eta平方的问题、omega平方的历史，以及为什么它没有得到充分利用。然后，我们使用受试者内部因素和/或受试者之间因素，为具有固定因素的方差分析设计（包括单向、双向和三向设计）提供了一个关于ω平方和偏ω平方的用户友好指南。我们展示了如何使用SPSS的输出计算ω平方。我们提供有关置信区间计算的信息。我们研究了非相加性问题，以及内在因素与外在因素的关系。我们认为，统计包开发人员可以在简化ω平方的计算方面发挥重要作用。最后，我们建议研究人员报告用于计算效应大小的公式，如果可能的话，包括置信区间，并在他们工作的在线补充材料中包括方差分析表。（PsycInfo数据库记录（c）2023 APA，保留所有权利）。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Psychological methods PSYCHOLOGY, MULTIDISCIPLINARY-

CiteScore

13.10

自引率

7.10%

发文量

159

期刊介绍： Psychological Methods is devoted to the development and dissemination of methods for collecting, analyzing, understanding, and interpreting psychological data. Its purpose is the dissemination of innovations in research design, measurement, methodology, and quantitative and qualitative analysis to the psychological community; its further purpose is to promote effective communication about related substantive and methodological issues. The audience is expected to be diverse and to include those who develop new procedures, those who are responsible for undergraduate and graduate training in design, measurement, and statistics, as well as those who employ those procedures in research.