Actually, your wrong.  Once you get a certain number of samples.  Your statistical formula is vastly more important then getting more samples unless you are getting a large number of samples.

For example NPD probably refuses data from more smaller buisnesses they can use as sources because they don't want to mess with their formulas until they do a yearly data reliability test vs total shipped numbers.  No nede to screw up your whole formula just to add 2 stores in minnesota.  Or to change your formula if your undertracking a console because you risk screwing it up even more until you have an entire year to see if your overtracking it consistantly or if your formula needs a major overhaul in some areas.

Hence i imagine that's why Ioi is keeping the numbers like they are, it seems right now that the 360 is being undertracked vs MS's internal data, and since VGchartz isn't paid for their numbers they can take the risk of changing their formula more often and if mistakes are made just change the historical data. 

Maybe all the overtracked 360's are just the number of xbox's people are buying to replace their RROD ones? ^_^

 Well I'm not happy with our 360 numbers which I've beent stating have been overtracked for awhile.

I mean no offense but there is obviously some kinda discrepancy if last month we undertrack in comparison to NPD for 360 and then this month overtrack in comparison of NPD for 360. 

Well ,I am going to bed good night (its 2 am here ) to everyone .

So the PS3 is 5,000,000 behind the 360 in America, and it's catching up by about negative 250,000 a month.

At that rate, the PS3 should pass the 360 in April of 2005.

Well ,I am going to bed good night (its 2 am here ) to everyone .

Yeah, the discrepensy is that Ioi changed his formula after being giving some shipped 360 numbers.  Atleast that's what i get out of it.

*was munching on some popcorn, but then the site crashed on him

Anyway, there's a variety of possibilities, and we probably won't get a somewhat definitive answer until we get it straight from the horse's mouth (by that, I mean the manufacture quarterly ship data, our adjustment usually happen around there). NPD is hardly the horse's mouth, they calculate the numbers just as we do, and do keep in mind that in statistics, a distributed sample is far more important than isolated sample, and that percentage means nothing little (unless someone get 100%, then it's fact) after the sample size passed a certain number (was it n > 30 or something?).

The only reason we'd this site get so off number is most likely from statistical bias, basically the retailers we end up tracking affected the sales either due to retail chains (if ioi is 100% honest, which I believe, this should not matter) or regional difference. Edit: It's also possible that the company responsible for shipping these consoles done a really crappy job and we end up overtracking number because of the difference in perception to sell-through? (improbable)

Personally, I believe the number are somewhere in between, and will await to see how this comes out when the quarterly are finally released. There's really no right nor wrong right now.

On a side note, have NPD ever change their monthly data after publishing it?? 

Edit/Quick Summary: All above thoughts does not mean that I think neither NPD nor Vgchartz is necessarily wrong, it's basically undecided since this isn't exactly an easy period to track.

P.S. Have some patience, everyone's argument so far amounts to some kind of personal belief instead of any actual facts. I know you don't want to believe some console other than your favorite is doing that much better if there's an alternative that shows it's lower or vice versa, but that hardly make your assumption any better. Tune the fanboyism down a bit and we can have a proper discussion.

P.P.S. Pardon the wall of text 

 ioi I'm disappointed that you refuse to update your "tracked" data based on the official data from NDP. NDP is the official entity in this matter and they have more data then anyone else (60% is more than enough for pretty accurate tracking).

Also, you are using Sony's shipped to retailer numbers to justify your undertracking of the PS3 sales but you actually overtracked PS3 too. NDP number for BOTH the 360 and PS3 are lower than yours. Please don't use the shipped numbers and compare them to VGC and NDP. We know it does not work like that.

The fact that your data is wrong is not bad, most of the time you guys are pretty close to the mark. The bad part is that you refuse to update the data to reflect NDP numbers. I like to come here and post my annoying fanboy posts in the forums. I like to brag about your site to my friends and co-workers. I like to defend VGC when I see people contesting the data in other gaming sites but refusing to update data when your data is clearly wrong for a full month is going to change the way I look at this site.

 I hope you reconsider and adjust your data accordingly to the official numbers.

whats the point of this site if loi just automatically changes his data to be in line with npd?