I thought I'd check in with PS4 WW:NPD sales ratio again since Sony gave us another number. Apparently on Dec 3 they said they'd sold 70.6 million PS4's.
https://www.playstation.com/en-us/c...n-4-sales-surpass-70-million-units-worldwide/
Now that November NPD is in I have PS4 at 21,841k in US through November. So 70.6/21.841=~3.2 ratio.
So yep, these ratios established last gen continue to hold almost exactly. On Nov 6 2103 Sony announced 80 million PS3's sold (sell in).
http://us.playstation.com/corporate...3-sales-reach-80-million-units-worldwide.html At that point I had them at 24,848k NPD sales. Which is...3.22 ratio WW:NPD.
One caveat though is now Sony sales PR says "sold to consumers" where in 2013 they said "sell in". So there will be a difference in there in favor of PS4 (80 million "sold in" means something less than 80 million sold to consumers) although it should not be too large. Apples to apples the PS3 sold to consumer ratio might have been 3.0-3.1 (if we assumed VERY conservatively 80 million sold in meant 75 million sold to consumer as of 2013 PS3 PR, that would be roughly 3:1).
Another caveat is that NPD sales leaks have become so janky over the years they are estimates with a fair amount of error.
If Microsoft's 2:1 shipped WW:Sold NPD ratio continues to hold (almost certainly given how well these ratios hold up in all testable cases) they are at 18,766k NPD after Nov 2017. So they would be around 37.5 "sold in" AKA shipped WW through November. December (should be another 1-1.5 million sold NPD) will push that to at least around 40 million sold in WW.
I even have an idea that since Playstations WW:NPD ration appears to have crept up ever so slightly, Xbox's might be doing the same (I have another small bit of info for this I wont get into). Since after all third world markets like South America, Russia, and China may be growing a bit. But, given the slop in any of these estimates they probably aren't precise enough to bother drawing conclusions like that.