sagefr0g said:
i think i see my mistake where i was askin, wouldn't the units of the term then end up (std/rnd)* [square root (rnd)] = (std)*[square root (rnd)/(rnd)]?
i think what it is, is that when you do the mathematical operation that the math only operates on the numbers not the units. duh
so really in my question it would be (1std)/(1rnd)* square root(1)rnd = 1(std/rnd)*1(rnd) = 1sd = sd .
edit:
but i'm still confused on this units conversion thing cause i know there is stuff like square feet and meters^2....
like isn't 2M * 2M = 4M^2 (ie four meters squared)
Well, to tell the truth, that last paragraph I didn't really look at lol.
I've never had a head for variables anyway lol. All those x's and y's. I need 2's and 4's lol.
So maybe it might make sense lol.
Whether SD/rd is in $'s or units, the math is the same as far as I know.
But, I was thinking of what you said when I got up today, for some reason, when you said " variance is convoluted enough cause what do you got to do to get it? square the differences from the mean or ev or something like that."
summed up so perfectly my understanding of the subject lmao.
However, I sort of think, all that squaring stuff doesn't really relate to geometry and the area of a square. Although I would call a square 2M on each side has an area of 4 square meters rather than 4 meters squared lol.
I think that squaring stuff is just, maybe, some kind of convenience so one doesn't have to deal with a negative number when it is left of expected.
So, maybe with a mean of 6 and one result at 4, it's obvious it varies by "-2" from the mean, just as a result of 8 would also vary by "+2" from the mean.
So, both are 2 things away from the mean - they "vary", the total variance in both cases is "2", 8 is as far away from 6 as 4 is far away from 6, the same distance from the mean.
So if you square "-2" or "+2", you still get 4. You can't take the square root of a negative number becasue two negative numbers when multiplied together always produces a positive number. (Another act of faith on my part lol.).
So, in this case, whether the result is "4" or "8", the SD is square root of 2 since the variance is "2" in either case.
And, before you ask, I have no idea why 1SD always means a result, either that far left or right from expected, will fall within that range from expected 68%ish of the time lol. Maybe something to do with a bell-shaped curve wherein it is assumed all results are equally likely to occur. Or something.
PS. I did really, really bad at geometry. And even worse at probability. God how I hated probabilty. 40 years later and that's all I remember about it. I hated it. Still do. Never took a statistics course.
Which is, of course, the ultimate irony here. I can add, subtract, multiply and divide. I much prefer whole numbers but I can divide by fractions if I have to lol. I couldn't take the square root of 2, manually, if you paid me.
That's pretty much it.