Nielsen VideoScanWhen we brought back Ask Engadget HD, we told you the answers would go both ways. In case you couldn't guess, this is the variety where we answer your questions. We're going to start this off by explaining where Nielsen VideoScan numbers come from.

Nielsen is the leading provider of marketing information and thanks to its TV ratings it needs no introduction. The TV shows ratings have helped content providers decide which shows get canceled for some time. Starting in 1993, in cooperation with ACNielsen, the company started collecting movie sales information from most major retailers. Some of these retailers can report early, and this data is used to make up what's called First Alert, this is the data that shows up weekly in our Nielsen VideoScan HD movie post. The list of First Alert Retailers is very extensive and includes just about every major retailer including: Amazon, Best Buy, Circuit City, K-Mart and Target. But as many HD DVD fans will tell you Wal-Mart doesn't count. It's not that Nielsen doesn't want to count or that there's some blu conspiracy going on, it's just against Wal-Mart's corporate policy to share sales data. But despite what red fanboys will tell you, this does not invalidate the numbers -- they are expressed in percentages, and as any high school statistics student can tell you, unless Wal-Mart stopped selling Blu-ray movies entirely, the sale of HD DVD movies at one retailer alone wouldn't be enough to significantly change the outcome.

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