I have been tracking the Zack & Wiki sales figures, which while not impressive according to VG Chartz, the game is doing decent.  VGC has Zack & Wiki over 100,000 units sold but according an article on IGN, the numbers are 30,000.  That is a 70,000 unit difference, which seems to be too large of a spread.  Does anybody know why?

 Here is the article:

http://wii.ign.com/articles/841/841406p1.html

VGC overtracked the sales of Zack & Wiki.

NPD states that it sold 35,000 units in the USA in November. Add in Canada (maybe 4,000 units), and it's a 60k difference - of which wasn't made up in the 1 week that VGC has tracked extra in the US.

It's a mistake on VGCs part - it happens sometimes. ioi tracks 200+ games in the US alone....At that large of a software size to chart, some games slip through the cracks, as various games have various extrapolation methods, and ioi's polling sample is still rather low - low enough to over/underpredict some very niche titles, like Z&W.

Simple. IGN bought 70,000 copies, and vgchartz doesn't track IGN.

oops, mybad -- joke didn't work. 

As stickball was saying, individual video games are much much harder to track and guesstimate than consoles. Not only because they usually sell less than consoles do (excepting the PS3.... ok no more bad joke attempts from me) but also because the sales of individual games will vary wildly between store chains and between stores within a chain. Also NPD doesn't cover Toys R Us anymore and not only are they a major Wii game seller but they had a massive sale in November that caused virtually every Wii game they had to be sold. I'm sure NPD factored that in but how well? No I'm not trying to argue that accounts for the 60,000 unit discrepency.

Small sales numbers are going to be off more often because they magnify the small sample size errors. It also just so happens that Z&W in particular had supply issues at a lot of retailers while say the retailers we track had plenty of supply so those sales were probably extrapolated too far.

Wow ,some good games are doing like crap .Poor Zack and Wiki !

I had been hoping Z&W would be doing better. At least it has been in the top 25 Amazon Wii software since release... but that doesn't help Capcom decide to make a sequel, though. :(