I just thought this was pretty amusing. We've got a epidemiology stats test tomorrow, and emails have been flying over last minute questions. To cut the jargon, they give us a "shortcut" equation to calculate a rate, however the "shortcut" is unitless (you need unit time for a rate).

Anyway, I email this out, asking why the equation works without dimensions. The equation is basically: a/(a+b) - c/(c+d). A, B, C and D are the same units, so they would all cancel out. However, one of my classmates disagrees with me, saying the units in the denominator would be additive. In other words, 5 seconds plus 2 seconds is 7 double seconds.

Either I'm missing something major, or that's pretty sad.

That's only if you multiplied a and b in the denominator. Your friend is an idiot.

lol

well, not double seconds, seconds[sup]2[/sup] (i.e. for acceleration rate, which would not be the case here; you're right)

No, it's via addition. They really mean "2s" not "s[sup]2[/sup]". That's how stupid it is.

Unless they mean "s[sup]2[/sup]" with addition, which...

I mean, I don't know what would be worse.

I know what you meant, I was just trying to be .. not funny.

*tries not to get sick*

2+2=22?