these predictions are completely unrealistic. there is now way wii will sell 120m in north america alone thats about 1 in 4 people buying a wii. and the ps3 numbers are way to low as well

I doubt any system sells in as linear a fashion as this simple model assumes. But it's an interesting quick-and-dirty way to look at it. Actually if we look at historical data (much easier to do now thanks to this site), there aren't a lot of huge ramp-ups and ramp-downs in most consoles' lifespans -- they usually launch at one rate that may be relatively low or high, then settle into a gradually declining trend that's relatively linear. At least we don't often see the kinds of "game X will sure move consoles!" spike effects that a lot of people seem to expect. A similar rule of thumb I sometimes use to make rough predictions is to look at current sales ratios and translate to lifetime "catchup" terms. If one system is outselling another 4:1, and the generation lasts 6 years, then it will take the lower-selling system its entire lifespan to match the first 18 months of the higher-selling system's sales. You can't use these kinds of linear assumptions to do sophisticated market analysis or make accurate predictions -- but it's a useful way to look at trends. Is one system currently on track to pass another, or not? It's a way of deriving a useful week-to-week trend analysis in one's head without having to do a lot of math.

Maybe it wasn't clear from my post. This is NOT meant to be a serious way to predict sales. I find it hard to understand what 120,000 a week (Wii in NA) or 8,000 a week (PS3 in Japan) mean. But if the Wii sells 120K in each market each week for 6.5 years, it will sell 120 Million lifetime. If the PS3 sells 8K per week it will sell 8 Million lifetime. Obviously, that isn't going to happen, BUT it gets me a feeling for what numbers mean. Put another way. There really ARE about 1000 major-market weeks in a console generation. That's a useful little factoid to keep around when you are looking at weekly numbers.

To put it another way, I wish I had made my point as clearly as ddobson "It's a way of deriving a useful week-to-week trend analysis in one's head without having to do a lot of math." Exactly.

I don't think these are any where near a good guestimate The consoles sales are kinda like a tear drop. Quick to rise, hits a peak and trails off. There is no linearity about it.

Consoles don't sell consistanly each year tho. They could go up or down. Once they peak and start heading down then you can figure a rough final number.