I noticed in my Poker Tracker 4 database that my std. dev. (in BB/100) is lower at higher stakes. For instance, my std. dev. at 50NL is 78BB/100, and std. dev. at 100NL is 66BB/100.

My sample size isn't too big. Is it normal for std. dev. to decrease as one moves up? Anyone else who plays multiple stakes share their std. dev.?