[R-meta] effect size for proportion with respect to the chance expected

[Viechtbauer, Wolfgang (SP)]

Dear Patrizio,

What kind of 'effect size' do you want to compute? One could compute the difference between the observed proportion and the expected one (50/100 - .25), or one could compute the (log transformed) ratio (log((50/100) / .25)), or one could compute the (log transformed) odds ratio (log((50/100) / ((100-50)/100) / (.25 / (1 - .25)))), or ... So which one ar you interested in?

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On Behalf Of Patrizio Tressoldi
Sent: Thursday, 16 August, 2018 9:47
To: r-sig-meta-analysis using r-project.org
Subject: [R-meta] effect size for proportion with respect to the chance expected

Probably it is a trivial question, but I've have some doubts on how to
calculate the effect size and corresponding standard error or variance
of the difference between a proportion and its chance expectation, e.g.
n. trials = 100; n. hits = 50; chance outcome = .25.

Thank you
Patrizio