There’s this relatively old concept that has been gaining popular traction over the last decade or so, and it’s become increasingly popular across multiple disciplines and professions: the 80/20 principle. The general principle goes something like this: 80% of the effects come from 20% of the causes.  For those of you who are unfamiliar with the 80/20 principle, it may sound a bit odd, a bit speculative, perhaps even a bit pseudo-scientific.  But it actually stands on solid mathematical footing; and theory aside, you can observe it at work virtually anywhere. As an investor, it’s an important principle to bear in mind, not only because roughly 20% of your portfolio…