learn to speak about what you know and ask about what you don't know. The Americans here all understand what is meant by the shorthand term, Econ 101 (although the course I took was labelled Econ 1). I suspect the Canadians here would know the meaning of the shorthand as well. Others have explained the term to you so I don't have to.

Tequila, troops - that is trained troops - ARE a scarce resource. We simply don't have enough in theater to do what GEN McChrystal wants to do. In his analysis, he needs more of that scarce resource. From what I have read, we can come up with about 40k in relatively short order and still have troops available for other contingencies. But this number will stress the regenerative capacity of the Army and Marines. If we need more for this or some other contingency, where do we get them and what risk do we assume if we don't? The economists call this an analysis of "opportunity costs." BTW, although I usually make fun of economists for assuming away all the really important variables, in this case they really do make a contribution to our understanding of both the immediate problem and a useful link to the political cultural problem that we call (shorthand again) being casualty averse.

Cheers

JohnT