Sega's 150k figure, the publisher told us, was based on copies of the game shipped to retailers during that first week. Although a rep explained that this figure was "global," the only part of the globe the game was available in before July 10 (the UK launch) was North America. Those 72,000 units reported by NPD, then? Those were how many of the 150,000 copies shipped were sold-through to consumers (a.k.a. actually sold), according to Sega.
While this certainly makes the game's first week less impressive, we'll need to see how The Conduit did for all of July before delivering a fair verdict. We'll have those numbers as soon as the next NPD report hits.