Just on topic,

BOth VGchartz, NDP, Charttrac etc, use sampling to get to the numbers.

Last week Vgchartz reported that gears2 sold 2.1 million in the first 2 days. today Microsoft reported 2 million .

http://kotaku.com/5083952/gears-of-war-2-two-million-sold

so they do correlate.

There isn’t a 100% accurate way of tracking sales. The only way imo is the shipped figures released by companies. Those figures more or less indicate the need for the system although it diesn’t directly represent sales. Also, if stores are not selling Systems, they won’t order stock.

Supply and demand, say I am in the market for a PS3, and they were selling like hotcakes (wii) then I know I would not be able to get one cheaper in a few months, but if sales
are not good, a price cut might be in the pipeline in a
few months.

But you are right the only thing this show is that all the platforms are viable, and will be supported in the near future.

Not always, microsoft use ship to retailer and sony use ship from warehouse, so there will always be stock in channel differences.

Being in the industry I would like to clarify some question on the tracking methodology. Retail tracking as an instrument tends to be fairly accurate. While extrapolation is used by all players in the market one has to consider that this is usually only applied to small specialists. For example the tracking in South Africa is based around 70% on census level data meaning there is absolutely no extrapolation behind it. As a matter of fact it tends to be more accurate than publisher data because the market research companies involved have no vested interest. Again in South Africa the tracking for gaming software has a coverage ratio between 85% and 90%, on consoles it comes close to 96%