Cohen's D

(noun)

A measure of effect size indicating the amount of different between two groups on a construct of interest in standard deviation units.

Related Terms

Examples of Cohen's D in the following topics:

  • Cohen's d

    • Cohen's $d$ is a method of estimating effect size in a $t$-test based on means or distances between/among means.
    • Cohen's $d$ is a method of estimating effect size in a $t$-test based on means or distances between/among means .
    • Cohen's $d$ is an example of a standardized measure of effect.
    • Cohen's $d$ is frequently used in estimating sample sizes.
    • Justify Cohen's $d$ as a method for estimating effect size in a $t$-test

  • Difference Between Two Means

    • Two commonly used measures are Hedges' g and Cohen's d.
    • They differ only in that Hedges' g uses the version of the standard deviation formula in which you divide by N-1, whereas Cohen's d uses the version in which you divide by N.
    • Standardized measures such as Cohen's d and Hedges' g have the advantage that they are scale free.
    • For example, Lenth (2001) argued that other important factors are ignored if Cohen's definition of effect size is used to choose a sample size to achieve a given level of power.
    • When the effect size is measured in standard deviation units as it is for Hedges' g and Cohen's d, it is important to recognize that the variability in the subjects has a large influence on the effect size measure.

  • Determining Sample Size

    • Cohen's $D$ (effect size), which is the expected difference between the means of the target values between the experimental group and the control group divided by the expected standard deviation.

  • References

    • Bem, D.
    • Cohen, J. (1988) Statistical Power Analysis for the Behavioral Sciences (second ed.).

  • References

    • Cohen, E.G. (1994).
    • Johnson, D.
    • Johnson, D.
    • Johnson, D.
    • In Cohen and Syme (Eds.), Social Support and Health.

  • References

    • Association of College and Research Libraries, & American Library Association. (1989, January 10).Presidential Committee on Information Literacy.Washington, D.C.
    • (n.d. ).Foundation for the Atlantic Canada English Language Arts curriculum.Retrieved October 2, 2007 from http://www.ednet.ns.ca/pdfdocs/curriculum/camet/foundations-ela.pdf
    • S., & Krathwohl, D.

  • Ethnicity

    • In 1978, Anthropologist Ronald Cohen claimed that the identification of "ethnic groups" in the usage of social scientists often reflected inaccurate labels more than indigenous realities:
    • Cohen also suggested that claims concerning "ethnic" identity (like earlier claims concerning "tribal" identity) are often colonialist practices and effects of the relations between colonized peoples and nation-states.
    • Criticize the concept of ethnicity from the perspective of Max Weber's and Ronald Cohen's theories of social constructionism, referencing the approaches of primordialism, perennialism, and constructivism

  • Further Discussion of ANOVA

    • Jacob Cohen, an American statistician and psychologist, suggested effect sizes for various indexes, including $f$ (where $0.1$ is a small effect, $0.25$ is a medium effect and $0.4$ is a large effect).
    • Compound comparisons typically compare two sets of groups means where one set has two or more groups (e.g., compare average group means of groups $A$, $B$, and $C$ with that of group $D$).

  • Distribution-Free Tests

  • Panic

    • The term was coined by Stanley Cohen in 1972 to describe media coverage of Mods and Rockers in the United Kingdom in the 1960s.