Yeah, sorry about that.  The whole graph wouldn't fit in the OP.  Click on the graph link in the OP or see blacksaber's post above for the full thing.

Hey, I like math. Lets run with some real numbers:

Tip #1 Look at the whole graph (if January isn't showing, they aren't January's numbers
Tip #2 Get America's numbers from January

Wii: 21% / 21M = 1.00% total playtime per million consoles
360: 18% / 16.2M = 1.11% total playtime per million consoles
PS3: 9% / 7.8M = 1.15% total playtime per million consoles

Conclusions:
According to this data the PS3 is played most per console with the 360 3.5% back and the Wii 13% back.

@lapsed
ringo already figured it out.
the usage is higher due to there being more users on the wii due to it being a party system.
Nielsen families are given codes for everyone to put in while they are playing. Every hour spent on wii with 3 other friends accounts for 4 total hours.

Whereas ps360 owners are more likely to play by themselves online.

That is how an owner can play less by himself, but that total minutes played for all users can be higher.

Which is backed up by the claim from Nielsen that everything else was right and also that nothing else was contested by that other group.

Here is what the corrections to the graph are:

-- The points for Xbox 360 and Wii usage were reversed in January 2009 only in the original.

-- The lines for GameCube and PS3 were reversed in the entire graph.

What the graph is telling me.

Over the course of a year, the PS2 has lost a lot of playtime -- it went from more than one-third of all usage to less than one-quarter. It still is the most used machine, but probably not for long.

The Wii and PS3 have seen almost a doubling in usage. The PS3 now holds 8-9%, up from 5-6%. The Wii holds 21%, up from 12%. These two consoles appear to be benefiting the most from the decline of the PS2.

The Xbox saw slow but steady growth but appears to have leveled off at 19-20%.

Older systems still see playing time. Roughly one-sixth of usage is on other systems (DC, PSX, N64, classics ....). Meanwhile, the Xbox and GC have seen small drops recently after being mostly stable through 2008.

What the chart is not telling me is how much people are GAMING!

That's right. It talks about how much they are using their consoles. If you use your PS2 as a CD player or your Xbox as a DVD player (like I do) -- that shows up as usage. The article notes this. Most posters do not.

This point is particularly important with regard to the use some of the newer consoles. Both the Xbox 360 (streaming) and the PS3 (BR-DVD) have enhanced movie viewing capabilities. That entertainment use may distort their usage statistics -- and even Nielsen notes that.

Mike from Morgantown

@mike
this new thread shows those stats in rough approximation. I will link to the original as well, which are defended as true by nielsen.
http://www.vgchartz.com/forum/thread.php?id=67461&page=1

Please don't go to that thread. You are ignoring my math completely saying Xbox360 usage is 20-30% higher. Math please!

I already answered your post lapsed. Look at the truth for christ sake. The numbers don't match because of the data collection method.

So... you take numbers (quantifiable) and then thow in some assumptions about the number of multi-play sessions per console (did I miss those numbers?) and put them in in your results?

I am just going off numbers. Yes those numbers include a majority (I don't know how much) of Wii sessions vs other consoles that include multiple players, but they also include a majority (again I don't know how much) of other console owners vs Wii owners that use the console for something other than gaming.

All we have is the numbers. Don't mix in assumptions.

Edited for clarity.