You know I'm no good at math. I even make my students double-check their grades on tests and essays, to make sure I haven't accidentally mis-added their points and given them the wrong grade. Sometimes I even write tests that don't add up to 100 points. And it takes me about 40 minutes to balance my checkbook - which is bad if you consider I've got an excel doc that supposedly does all the calculating for me.
But here's my thoughts on your formula, regardless.
First, I think you need some kind of factor to take into account the decreased efficacy of coffee relative to the increased number of cups consumed.
Second, you might need to take into account the increased efficacy of coffee relative to the decreased amount of sleep. I mean, I know that the longer I haven't slept, the more one cup of coffee here and there does wonders.
Third, what about additives? The more milk I put in coffee, the more I can drink (the thicker the lining of my stomach, thus the more acids I can feed it).
And what about coffee taken in conjunction with food? Does that increase or decrease the efficacy?
So, I guess all my factors relate to efficacy of coffee. But you know, having worked many, many years on and off in bakeries, I can attest to the fact that not all coffee cups are created equal. No matter what the government may say.
your I'm-sitting-at-HDC-because-I-don't-have-internet-at-home-and-this-probably-could-have-been-a-longer-post-but-I-want-to-go-home-and-go-to-sleep-and-thus-decrease-the-number-of-cups-of-coffee-I-drink-tomorrow sister