[R-meta] Percent Correct as outcome variable

[Markus Janczyk]

Dear everybody,

We are interested in a meta-analytic question related to memory research.

Consider the case where two conditions X and Y are compared. 
Unfortunately, in many of the (old) papers only the means M_X and M_Y 
are reported for the percent correct remembered items (and often not 
even the interesting t-test). To calcutale a "real" effect size as the 
outcome measure to use in a meta-analysis, we need to some variability 
measure though (if I understood the metafor functions right). With the 
data we have, it feels like a raw (and non-standardized) effect we can 
caluculate as the outcome variable (i.e., D = M_X - M_Y).

Is there any other possible solution or improvement somebody knows of or 
recommends or just somebody who can let me know a reference where I can 
look?

Thanks, Markus

-- 
Jun.-Prof. Dr. phil. habil. Markus Janczyk, Dipl.-Psych.

University of Tübingen
Department of Psychology
Cognition and Action
Schleichstraße 4
72076 Tübingen
Germany

http://www.pi.uni-tuebingen.de/arbeitsbereiche/kognition-und-handlung/research-group.html
email: markus.janczyk at uni-tuebingen.de
phone: +49 (0)7071 2976761