[R-meta] effect size similarities

Patrizio E Tressoldi p@tr|z|o@tre@@o|d| @end|ng |rom un|pd@|t
Wed Jun 23 09:41:52 CEST 2021

Il 23/06/2021 09:28, Viechtbauer, Wolfgang (SP) ha scritto:
> I understand. What I tried to say is that this equation does not apply for a one-sample t-test. Cohen's d is
> d = (mean1 - mean2) / SD,
> where mean1 and mean2 are the means of two groups and SD the (pooled) SD and hence it reflects the difference between two groups. If there is only one group, then Cohen's d cannot be computed.
In Lakens (2013) it is stated: "The effect size estimate Cohen’s dz can 
also be calculated
directly from the t-value and the number of participants using the
formula provided by Rosenthal (1991): Cohen′s dz = t√n

Lakens, D. (2013). Calculating and reporting effect sizes to facilitate 
cumulative science: a practical primer for t-tests and ANOVAs. Frontiers 
in psychology, 4, 863.


Patrizio E. Tressoldi Ph.D.
Science of Consciousness Research Group
Studium Patavinum
Università di Padova
Padova - ITALY

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