NPD uses a statistical process. Period. There is no other way unless all game consoles and software go through one person's hands and they count every title and every piece of hardware that they sell. I'm sure NPD's statistics are quite sound as they have both a large sample size and enough history to correct for unforseen anomalies. That said, it is a statistical estimation just the same. I would be willing to bet that NPD is NEVER better than +- 5% of actual sales in any month-long period for software. They may do better on hardware, though. Wal-mart is a big question mark in the numbers as they apparently don't report to NPD so NPD truly has to estimate those numbers... Those that take NPD as "actual" aren't thinking clearly about what they really do.

For any of you that actually understand statistical sampling, I would be interested (we'll never know, of course because that is their secret sauce) in what NPDs confidence intervals are. For the laymen it is basically a number expressed as a percentage that indicates how confident the person doing the analysis is that their results are "correct". I.e. we are "90% confident that the sales of guitar hero 3 for the PS3 are between 90-110K for October." Some people don't want 90%. They want 95 or 99%. As you push the percent confident up, it requires a larger sample size. a 100% confidence level would, of course, required 1:1 sampling which isn't possible.

So, in sum, NPD (and VGC for that matter) take a sample, analyze it, apply some statistics to arrive at a mean and then shoot for a confidence interval they can live with. NPD is reporting their mean number above of 100K (they leave out the +- 10K of course).

To be clear, the quarterlies I was talking about were the ones Nintendo/Sony/MS put out.

They are hard shipped numbers which means they are absolutely accurate numbers to check our accuracy against rather than NPD numbers which are just another estimate. I'm not saying that NPD data wasn't helpfull early on to get things refined but I think we are to a point where NPD data is innacurate enough that it can't help refine the process any more.

And for those who don't know, increasing sample size provides a diminishing return. So VGC doesn't need to get its sample sizes up to the level of NPD to be close to it in terms of accuracy.

I don't know how many retailers there are out their but if we assume 20k and say that ioi is tracking at 10% then the standard error is something like 0.64% compared to polls people accept for politics that are in the 3.5%-5% range.

If ioi is tracking down as low as 1% of that 20k things change and the standard error is about 7%.

Granted I am not exactly a professional on this stuff, and I am making some assumptions on the size of the population but those numbers aren't going to change a whole lot anyways since they are based on %s.

I'd guess more often then not NPD will get it closer more often then VGcartz, but do to the nature of the buisness, this isn't going to be the fact 100% of the time... as it seems likely the case recently do to the released numbers like Ioi said. Later on, it's likely they'll be more accurate.. it really depends on the formula they are using.

That's the trick really. You can do this, have a much larger base, and still be less accurate depending on what kind of equation your using. The problem places like NPD have is that they are paid for their sources... so they don 't want to tinker too much with the formula because if they go too far one way and way over shoot they're going to lose a lot of buisness.

If NPD and an independent site that wasn't free both had 60% of the market... i'd bet on the independent site being more accurate because they would be more willing to tinker with their formula to get it closer, instead of saying something is "close enough."

How about this theory - NPD decided to stop giving away data that they charge for ...

By going to quarterly releases to the public it makes their monthly data that much more valuable to those that may want to purchase it. At the end of the day the Video Game section is a small part of NPD's market research and I doubt that the decision was based on anything more than making their product more valuable.

Just to pose the question:

Who the hell cares if NPD is more accurate to begin with? They aren't going to provide you any data anymore anyways folks.

If you have been reading the net and have taken up the anti-VGC propaganda touted by several people then I would challenge you to ask yourself what you have personally seen done that would validate your position. And once you realize that you haven't seen anything and you were taking the word of someone else at face value I would challenge you to look around the site for something and see if you can find something wrong when you look. I'm not talking about small things, as ioi has admitted to this being a work in progress, but rather something that indicates to you that these numbers are completely fake.

And once you are done if you realize that you had trusted someone else's opinion without any proof and that when looking closely at this site you still couldn't find anything to indicate that these numbers are anything but an honest attempt at estimating I would ask you to take that as a lesson to never just take the word of someone you read on the internet at face value. Because this whole debacle where the VGC name is smeared across the net is due to a few bitter people who were able to convince folks who were willing to believe what made them happy.

Someone mentioned NPD would have historical insight into Wal-Mart sales, but I think with the way Nintendo has changed the industry in the past couple of years, that historical insight may not be valid anymore. Nintendo has not only taken first place in hardware, but it is also arguably changing who buys the systems. If grandparents and moms are really buying Wiis for themselves now, they probably aren't getting them at GameStop.

I think kn and Quaid have some good theories on what NPD is trying to achieve.

"I doubt that the decision was based on anything more than making their product more valuable."

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I think it has to be much more complicated than that, because their customers don't pay $20,000 per month just to see a top 10 list once a month. Seriously, do you think there was anybody on the fence now saying "Oh shit we REALLY need that top 10, better fork over the 20 grand". Even if there were, do you think it would make a significant difference to NPD's bottom line?

The real meat of NPD is customizeable highly detailed reports for corporate accounts. Top 10 lists are worthless to high level execs.

 Aww thanks

You bring up a very good point yourself. it crossed my mind previously but I didn' t think to mention it in my post. I also believe that Nintendomination has played a big part in NPD's decision, either directly or indirectly. As you allude to, Nintendo has made efforts to get their hardware sold in new retail outlets not traditionally associated with games. (Wii in Bed bath & Beyond? LOL). Thus Nintendo's new efforts would not be tracked by NPD and I'm sure NPD is not happy about that. 

 Also there is more than a small possibility that some of NPD's other customers are not happy with the publication of sales data that does not jive with their PR campaigns.

Crazy fanboy talk? Think what you want. But it is fact that the videogame industry is by far the most shady of any entertainment industry. Just take a look at the video clip of Jack Tretton getting humiliated on CNBC.

@ Quaid - I understand what you are saying ... but by the same argument - monthly top 10 is more or less irrelevant to NPD's paying customer - it is NPD data and becomes more valuable with less exposure ...

Maybe some marketing grunt at NPD sold the idea that the monthly data does have some intrinsic value and can be revenue stream on its own.

I just don't buy into the argument that the action was directed at VGC specifically. I find it much more plausible that NPD decided to keep their data to themselves - especially over the 4th quarter holiday - and go public on a quarterly basis to keep a public presence.

Regardless of the reasoning the quarterly discussions are going to be interesting to watch - especially when the variances are significant.

My guess, they do not want to be embarrassed by thje Vgchartz Figures