Well the GCN marketshare has to be 37%, which would most likely mean a drop in both PS2 and XBOX marketshare. I just took an educated guess on what the marketshare of PS2 compared to Xbox would be, assuming PS2 marketshare for October was down 10% since September, which i think i read somewhere. But your right, all the numbers do seem a bit high, ill try another way.
Nintendo said they sold 4 times the number of GameCube straight after the pricecut. Soooo
September sales by week:
Week 1 = 17,500
Week 2 = 17,500
Week 3 = 17,500
Week 4 = 43,750 (17,500/2 + 70,000/2) (price cut halfway through week + other factors)
Week 5 = 70,000
Adds up to 166,250 (TRST number = 165,000, close enough). Nintendo said October sustained these numbers, so that would mean in October (October is a four week NPD TRST month) would look something like this:
Week 1 = 70,000
Week 2 = 70,000
Week 3 = 70,000
Week 4 = 70,000
Total 280,000. Sounds a bit more reasonable doesnt it? But, the increase has been by at least four times the amount, so that probably means more GCs were sold than that, but there is no factual evidence i can manipulate into that, so 4 times will have to do. Now, assuming 280,000 Nintendo GameCubes were sold in October, and Nintendo GameCube had a 37% marketshare that month:
PS2 334,000
GCN 280,000
XBX 172,000
Another thing, im not taking into account the increases/decreases over the year, just from the past month(s).