to rate the strength of a military you must multiply quality by quantity. if army Red has twice as many tanks as army Blue, but army Blue's taks are twice as good as army Red's (ie for every one army Red kills Blue kills two), then Red and Blue are equal in strength.
to rate a contry in any sence, I think you must look at three defineing charicteristics:
1) economy
2) population
3) military strength
all three of these items are equaly important (though relateing them quantitivly to each other is somewhat hard to determine). what you are trying to determine in rateing may make a sloight scope change, but you'r still going to look at these three features, and oftine they relate to each other.
to rate the "greatness" of a contry, I'd say you'd need to look at:
1) economic stability - are there job, do they export more than they import and by how much
2) liveing standard - are the people literate, what's the GNP, cival liberties
3) military - how well can they protect 1 and 2 from someone who'd like to come in and rape them
if you want to gauge a contry's strength/importance, I'd say you'd need to look at
1) how much of the planet's total population do they represent
2) how much of the planet's work do they do
3) how capable are they to ether defend themselves or atack others
in this respect, I generaly think America is roughly equivilant to China, and (all of it, though they might be slightly higher in total) Europe(lets through Japan and Astralia in there too), Russia (not counting it in europe) is less than half, probly closer to a fourth of any one of the big three (USA, China, and Europe), and all of the rest of the world combind (Africa, South America, ect; and this is mostly becase they arn't organised as a cohearant power) would probly reach about one of the big three in terms of strength/importance.
