stats help trying to find an overall standard deviation.

C

hi there, does anyone know if this is possible.

I have a list of 12 mean and standard deviations for t-scores. I want to get the overall mean and SD of these, but I don't have the raw data as they're in a journal. Can it be done?

Trying to get them to do a power calculation. Guess otherwise i'll have to do 12 power calculations!

H

Contact the author?

R

Hi,

probably naif yet can you not add them all up and devide by 12 to get the overall mean?
Regarding SD for all one can use excell to calculate this from your 12 figures.
Please shoot me if I am totally wrong!

8147