Eta- and partial eta-squared in L2 research: A cautionary review and guide to more appropriate usage

Reza Norouzian, Luke D Plonsky

Research output: Contribution to journalReview article

16 Citations (Scopus)

Abstract

Eta-squared (η2) and partial eta-squared (ηp 2) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013). Consequently, it is critical that these effect sizes are applied and interpreted appropriately. The present study examined the use of these two effect sizes in L2 research. We begin by outlining the statistical and conceptual foundation of and distinction between η2 and ηp 2. We then review the use of these indices in a sample of published L2 research (K = 156). Among other results, we show that ηp 2 values are frequently being mislabeled as η2. We interpret and discuss potential causes and consequences related to the confusion surrounding these related but distinct indices. Within the context of reform efforts in quantitative L2 research, the current study seeks to respond to the recent, pointed calls for improving study quality (Plonsky, 2014) and statistical literacy (Loewen et al., 2014) in the field.

Original languageEnglish (US)
Pages (from-to)257-271
Number of pages15
JournalSecond Language Research
Volume34
Issue number2
DOIs
StatePublished - Apr 1 2018
Externally publishedYes

Fingerprint

statistical test
quantitative research
literacy
reform
cause
language
Values

Keywords

  • effect size
  • eta squared
  • partial eta squared
  • quantitative L2 research
  • statistics

ASJC Scopus subject areas

  • Education
  • Linguistics and Language

Cite this

Eta- and partial eta-squared in L2 research : A cautionary review and guide to more appropriate usage. / Norouzian, Reza; Plonsky, Luke D.

In: Second Language Research, Vol. 34, No. 2, 01.04.2018, p. 257-271.

Research output: Contribution to journalReview article

@article{7a32986ea34644aea051ac33a4a45b0b,
title = "Eta- and partial eta-squared in L2 research: A cautionary review and guide to more appropriate usage",
abstract = "Eta-squared (η2) and partial eta-squared (ηp 2) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013). Consequently, it is critical that these effect sizes are applied and interpreted appropriately. The present study examined the use of these two effect sizes in L2 research. We begin by outlining the statistical and conceptual foundation of and distinction between η2 and ηp 2. We then review the use of these indices in a sample of published L2 research (K = 156). Among other results, we show that ηp 2 values are frequently being mislabeled as η2. We interpret and discuss potential causes and consequences related to the confusion surrounding these related but distinct indices. Within the context of reform efforts in quantitative L2 research, the current study seeks to respond to the recent, pointed calls for improving study quality (Plonsky, 2014) and statistical literacy (Loewen et al., 2014) in the field.",
keywords = "effect size, eta squared, partial eta squared, quantitative L2 research, statistics",
author = "Reza Norouzian and Plonsky, {Luke D}",
year = "2018",
month = "4",
day = "1",
doi = "10.1177/0267658316684904",
language = "English (US)",
volume = "34",
pages = "257--271",
journal = "Second Language Research",
issn = "0267-6583",
publisher = "SAGE Publications Ltd",
number = "2",

}

TY - JOUR

T1 - Eta- and partial eta-squared in L2 research

T2 - A cautionary review and guide to more appropriate usage

AU - Norouzian, Reza

AU - Plonsky, Luke D

PY - 2018/4/1

Y1 - 2018/4/1

N2 - Eta-squared (η2) and partial eta-squared (ηp 2) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013). Consequently, it is critical that these effect sizes are applied and interpreted appropriately. The present study examined the use of these two effect sizes in L2 research. We begin by outlining the statistical and conceptual foundation of and distinction between η2 and ηp 2. We then review the use of these indices in a sample of published L2 research (K = 156). Among other results, we show that ηp 2 values are frequently being mislabeled as η2. We interpret and discuss potential causes and consequences related to the confusion surrounding these related but distinct indices. Within the context of reform efforts in quantitative L2 research, the current study seeks to respond to the recent, pointed calls for improving study quality (Plonsky, 2014) and statistical literacy (Loewen et al., 2014) in the field.

AB - Eta-squared (η2) and partial eta-squared (ηp 2) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013). Consequently, it is critical that these effect sizes are applied and interpreted appropriately. The present study examined the use of these two effect sizes in L2 research. We begin by outlining the statistical and conceptual foundation of and distinction between η2 and ηp 2. We then review the use of these indices in a sample of published L2 research (K = 156). Among other results, we show that ηp 2 values are frequently being mislabeled as η2. We interpret and discuss potential causes and consequences related to the confusion surrounding these related but distinct indices. Within the context of reform efforts in quantitative L2 research, the current study seeks to respond to the recent, pointed calls for improving study quality (Plonsky, 2014) and statistical literacy (Loewen et al., 2014) in the field.

KW - effect size

KW - eta squared

KW - partial eta squared

KW - quantitative L2 research

KW - statistics

UR - http://www.scopus.com/inward/record.url?scp=85036564781&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85036564781&partnerID=8YFLogxK

U2 - 10.1177/0267658316684904

DO - 10.1177/0267658316684904

M3 - Review article

AN - SCOPUS:85036564781

VL - 34

SP - 257

EP - 271

JO - Second Language Research

JF - Second Language Research

SN - 0267-6583

IS - 2

ER -