Hello,

If you like me to help, please send me an email to [email protected]

I try my best to help out.

cheers

Amir

Dear Emilio

You can do that as effect sizes can be converted to each other. But I think giving two pooled effect sizes based on difference in means and correlation sounds more prudent.

After all difference in means and correlation ARE different and I am not comfortable with pooling them together.

Ramin

Yes, you should be able to analyze these in the same model - as you say, Hedge's d (for a dichotomous IV and continuous DV) and correlation coefficiencts (two continuous variables) can be directly transformed from one to the other. If you are concerned, you could look at this as a potential moderator variable - though if you found differences you'd want to be careful in interpreting them (e.g., if most studies reporting Hedge's g are experimental designs and most studies reporting a correlation coefficient are not, then that could be the difference). Having said that, this is an empirical question - I wouldn't start of with the assumption they can't be combined - test that assumption.

Thanks everyone ! I have been thinking about all yours answers.

To Keegan: what does it mean ? Good question ! My variable is the consumption by herbivore in presence of neighboring plant. Which is what both effect size types can answer. But I agree this is not a perfect fit.

I will thus do as Steven suggested : using effect size type as a moderator, at least if my sample size is sufficient for this. I think it will, but I still have a lot of work ahead of me to be sure.

Hi everyone,

Some of my recent reading helped me (a lot). For those interested, I suggest this excellent book :

Card, N. A. 2012. Applied meta-analysis for social science research. - The Guilford Press, New York. 376 pp

HI Emilie!

another excellent book is:

Michael Borenstein, Larry hedges, Julian PT Higgins, Hannah R RothstaIN

Introduction to Meta-Analysis

Wiley 2009 ISBN 978-0-470-0574-7(H/B)

Dear Emilie,

This is possible using the Hedges'g, which standardizes the individual effects sizes, even if presented differently. However, the use of Hedges´g creates a standardised measurement that not represent a particular unit (in my case: kg/m2, when I used).

Best,

PH

Hi everyone,

I wanna ask what happened if I don´t find the SE (standard desviation) in the papers? Wich effect size can I calculated without it? Because most of the publications I selected, have means but don´t have SE and just some of them give t-student, chi or other stadistic.

I am reading Rosenberg et al 2000. Apparently I can calculate other effect sizes different from Hedge ´s d or Cohen´s d, but I am not sure if then I can use them all toguether. I mean, I have to chose one and calculate the same tipe of effect size for all the publications or I can use differents effect sizes depending on the data available in each paper?

Sorry, I can imagine the question is a little bit obvious, but I am just starting.