Considering that the sample questionnaires have to be administered by hand to each child, how would you scale the sample size for a study in this space?
It looks like the study that introduced the EQ-C and SQ-C in 2009 was only run on 1256 "parents of typically developing children" and 265 "children with Autism".[0]
Correlation of 0.2 is negligible with any sample size. The potential for invalid inferences is only pronounced by a small sample size. A samples size of a thousand is much better. But with n=100, r=0.2 there is a bigger chance that local factors influence the result than that the observed association says anything about human nature.
It looks like the study that introduced the EQ-C and SQ-C in 2009 was only run on 1256 "parents of typically developing children" and 265 "children with Autism".[0]
[0] http://docs.autismresearchcentre.com/papers/2009_Auyeung_eta...
[0 (alternate)] http://rd.springer.com/article/10.1007%2Fs10803-009-0772-x