# [R-meta] Question about obtaining correlation coefficient

James Pustejovsky jepu@to @end|ng |rom gm@||@com
Thu May 23 18:20:52 CEST 2019

```Joanne,

If you only have the M and SD of each variable, then no it is not possible
to calculate their correlation.

If you have the above, plus the M and SD of the difference between the two
variables, i.e., mean and SD of (B - A), then you can back out the
covariance and correlation. Or if you have M and SD of the sum (A + B), but
it seems less likely that the sum would be reported.

James

On Thu, May 23, 2019 at 11:17 AM Cath Kids <cathkidslover using gmail.com> wrote:

> Hi everyone,
>
> I am currently conducting a meta-analysis on the association of two
> variables (bias A & bias B) in high anxiety individuals. Theoretically they
> should be related but needs to be verified quantitatively. I used mostly
> pearson correlation coefficients. But in some studies, while the two
> variables were measured, only their means and SDs were reported.
> My question is, is it possible to calculate the correlation between bias A
> and bias B with just the provided means and SDs without covariance
> (assuming both variables are normally distributed)?
>
> I understand that it is possible to convert *d *to *r ,* but does it apply
> to this situation if the two variables are measuring related but different
> concepts?
>
> Thank you very much!
>
> Regards,
> Joanne
>
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>
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