Are returns factored into Nielsen's numbers?

[CasualCat2001]

When Nielsen/VideoScan provides the disc sale numbers, are returns subtracted?

If not, is there a separate statistic or company for tracking returns?

Intuitively, I'd expect "the other format" to have more returns and therefore more false positive "sales" due to purchases out of ignorance due to its name.

It would be nice if that intuition was quantifiable though.