effect size and percentages

[susie]

Hi,

Can you calculate effect size using percentages?

Needless to say, statistics baffle me.

Thank you very much!
S.

[AtlasFrysmith]

I'm not sure I understand your question--can you explain a bit more what you're trying to do?

[susie]

Sorry for the obscure question.

This could be a silly question but here it comes:

My means and standard deviations are in percentages. First I am not sure that using the percentages can be done. Second, if it can be done, I am not sure how to interpret the result - in other words - where does it fit on Cohen's definitions of "small" ..."large".

Here is an example:

Group A
number of subjects: 4
Mean: 12%
STDEV: 2%

Group B
number of subjects: 4
Mean: 39%
STDEV: 12%

So using these, I get the effect size of 3.62 (calculating Cohen's d from t-tests) ( I am comparing 10 groups in this way)

I am not sure if this is valid method or not.

I hope this is more clear. And thank you for looking into it.

S.