# Combining samples for EFA

#### mazendanaf

##### New Member
Hello,

I have conducted an experiment in two different countries. The experiment included a survey. The same survey was used. Is it valid to combine the two sets to perform exploratory factor analysis, or there will be a scale effect (e.g. as in the case of logit choice models).

Thank you

#### chiro

##### New Member
Hey mazendanaf.

Do you think there is any kind of correlation involved between the different data sets?

I ask this because if you some kind of correlation (especially intra-class correlation) then you will need to adjust for this when combining data from different sources.

If you assume independence and your analyses/models also assume independence then you can just combine them in the standard way: otherwise you will need a way to factor in the correlation aspects.