HappySqurriel said:
I will explain it to you a different way ... Nintendo, Microsoft and Sony all announce 100% accurate numbers which reflect the shipments of their hardware at a particular point in time; they're legally obligated to provide the most accurate numbers possible so they're very trustworthy. When you're trying to track sales to consumers what you're really trying to track is: (Sales to Consumers) = (Shipped) - (Unsold inventory) - (unsold systems) The unsold inventory can include the number of systems that are in retailer inventory, in transit, or possibly in the manufacturers warehouse depending on how the manufacturer handles their accounting. The size the unsold inventory is not a constant value, but it is a number which operates in a particular range depending on multiple factors; basically, a retailer is only going to accept so many consoles and a manufacturer is not going to stockpile years worth of inventory for no reason. The unsold systems include replacement systems and systems that were given away (or possibly sold through untracked channels). Unless you track 100% of the data at the retailer's end (which no one does), or unless your analysts are surprisingly lucky (in which case they should pick lottery numbers), you will have fairly large errors in your data that need to be adjusted. If you blindly continue on without consideration of what the shipped numbers actually mean in reference to the sold to consumer without adjusting your total and methodology you will (eventually) end up with either a number of systems sold that surpass the shipment numbers, or an unsold inventory that is entirely unrealistic. Right now your NPD numbers demonstrate (roughly) a 10% error for Wii numbers as of March 31st 2008 ... if they continue with a similar error rate eventually the number of systems they expect retailers to have in inventory will surpass the number of Wii systems sold in a year, or they will have the Wii's replacement rate at an unrealisticly high number (given that the majority of replacement systems are refurbished).
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Thanks for the post, i do however know all of these processes already. My original point to all of this was whilst one tracker will have slightly different data to another having one or two console significantly different to the rest seemed wrong. If all 3 consoles were say 500,000~ above npd i wouldn't have a problem. If all consoles were 500,000~ less then npd i wouldn't have a problem but having one almost the same which means it's sold as good as nothing in any where else whilst another has +500,000 and another +750,000 seemed wrong to me.
Take the japanese numbers for example:
media create wii- 6'262'090, ps3 - 2'175'021, xbox360 - 574'746
vgchartz wii - 6,302,583, ps3 - 2,232,612, xbox360 - 618,381
You can see that all of vgchartz numbers are slightly higher, and are wii 40,000~ higher, ps3 57,000~ higher and xbox360 44,000~ higher. They are all in the same range only being 17,000 in terms of difference between the highest and lowest number. That's fine and their's no problem and if i could find famitsu's total ltd numbers i'd compare them as well and i'd find similar data.
When european numbers from chart track and gfk get released vgchartz changes their numbers to be very close to them, however when npd's numbers are very different nothing gets changed and their is a big range between how close each console is, that's my point nothing more nothing less.
