The PS3 has half the install base of XB360, so the curve isn't going to be as steep. From that (messy) graph though, it appears to have 'gradient parity' with the XB360 version for the install base. PS3 sold about 400k in the first month, and XB360 about 800k. Factoring in the difference in install base, the curves match up.
Those are US numbers, and the launch aligned (which his data is) the PS3 had
more than half the install base (~2.4M to 3.4M as of November numbers launch aligned). I am not sure where you get the 400k/800k numbers for NA but my link has all the monthly/aggrigate sales data through September (bad server migration, no time to update the last couple months).
But I agree with Zassk, it isn't only that they "underachieve" (flatter/lower archs), but that there are fewer titles in the same similar window.
Not that it matters to publishers as a couple developers already voiced here: Launched aligned is nice in theory, but doesn't tell anyone where the industry is
today. They are looking at total potential now, not how things would have faired if they both launched together.
On another topic at hand (your are dismissed Mr. Shifty, this doesn't relate to you
), the last 4-5 months have put a kabosh on the suggestion that the PS3 was trending in the US like the 360 did in its first year (i.e. launch aligned). Unit sales lag 41% in relatively similar windows (launch aligned first year) in NA and is behind 325% in total current market share. The PS3 produced fewer million sellers in its first year compared to the 360 in its first year and the 360 has significantly outpaced the PS3 in 2007 software sales. So whether we compare NA 1st-year-360-to-1st-year-PS3 software/hardware data or look at a snapshot of the current market conditions, I think it is fair to say: the PS3 is lagging behind the 360, both relatively and absolutely, in NA. Ok, I had to get that out of my system... I had to wait a couple months for the firm data to confirm it, but hopefully we can file the, "The PS3 is doing just as well in its first year as the 360 did its first year" next to the "the 360 is the next Dreamcast"... and as for me eating some crow, I need to adjust my, "the Xbox 360 is trending 10% better than the Xbox" to "the Xbox 360 is trending nearly 18% better than the Xbox".
118% of 24M is...
That wouldn't put them on course to even break 45M in 5 years. Of course how generational sales tend to arch, 10% in the first year could mean significantly more down the road (think of it as a trajectory) so I will probably have to abandon my Xbox angle. Oh well, I only suggested it to demonstrate that 360 (hardware) wasn't the smashing
hardware sales success some have made it out to be. Software on the other hand...