Total GDP in PPP terms never made sense to me, except as an excuse to pump out news stories like this. GDP per capita PPP makes some amount of sense since it’s useful to get an understanding of what relative living standards are between two countries. But at the size of entire economies, there is no real purchasing power differential that would justify a PPP adjustment.
In non-PPP adjusted terms, China is barely half the size of the US but that makes for much less sexy headlines.
Does the PPP calculation take into account the fact that a lot of things that are easily available in the US are not so easily obtained in China? And the fact that China has an unfortunate habit of ignoring copyright and thus selling goods for cheaper than in economies that enforce such laws?
Anyway, if and when the US economy continues to recover no doubt the rather small differences will disappear, and so will stories like this.
I get the same feeling that I do about studies that the UN puts out - sometimes it seems like they are deliberating looking for some factor to include just so the US doesn’t come out no. 1.