I have conducted a meta-regression with SDM-PSI to investigate the change of brain activity as a function of age. I used the mean/median of age for each included study as the predictor. I guess this is the common practice and maybe the only way to do the meta-regression. However, I was criticized by the representativeness of the mean when the age range is relatively wide, such as the mean 40 for a range from 20 to 60. I am wondering whether there are any ways to account for the variance in the regression. And if possible, how to achieve that in SDM-PSI or metafor in R. I can think of a possible solution, that is, to adjust the variance of response variable with the variance of predictor. In other words, when the age range is wider, the variance of predictor variable is also higher. However, after a second thought, this may be problematic, considering (1) How to mathmatically adjust the variance in response varuable? (2) The variance of predictor should influence the certainty of the predictor itself, not the response. I appreciate any suggestions and discussions to this matter.

Dear Guochun, 

In regressions, even the simple ones, the variance of the regressors is not usually taken into account. You can try changing the values of the mean age for the lower or upper range and see if the effect changes.

Best,

Lydia

Dear Lydia,

Thank you so much for your reply. That is a great idea. 

Best,

Guochun