From December 2006 to December 2007, the Xbox 360 curve dropped by about 1.7 units. That means that the Wii cut the Xbox 360 lead by about 1.7 units in that time period. The average rate of change on the PlayStation 3 graph shows that during that same period the Wii gained a lead of more than 3.7 million systems over Sony's console.
From a mathematical point of view, these graphs are enticingly linear, enough so that one is tempted to make simple predictions based on them. Given the volatile market, especially with price drops and new models introduced as late as October 2007, the situation could change dramatically at the beginning of 2008. However, should the trends on this graph remain valid for the next 6 or 12 months, here are the estimated relative LTD figures:
* By mid-year 2008, PlayStation 3 would be behind the Wii by about 6 million systems and the Xbox 360 would still be ahead of the Wii by 1 million systems.
* By the end of 2008, PlayStation 3 would be behind the Wii by around 7.9 million systems and the Xbox 360 would essentially be tied with the Wii."