Has anyone here learned Standard Deviation? (math)

Probability and statistics shit. I twitched when I saw this.

 

Looks like something in my physics.

 

Looks like a bunch of shit.

 

That isn't standard deviation.

I remember it as this:

 

Standard deviations aren't that bad; summation notation just always looks messy.

I assume N is the number of elements in the set. Basically, it's just telling you to take each x, subtract the mean value, square it, and multiply by the corresponding probability of that x. Add whatever you get for x(1) to what you get for x(2), x(3), x(4), ..., up to x(N). Then, multiply by whatever N' is.

In the denominator, you're just adding the probability of each x together, and multiplying that whole sum by (1 - N').

I'd need to see the fine print for the definition of the other variables, but summation notation is just an easy way of writing repetitive operations; in this case, you start by computing the value where i =1, add it to the value where i = 2, add that to the value where i = 3, and keep going up to the value i = N. It really only starts to get ugly when you get summations of summations >.<

 

i learned it earlier this year but i forget it D:

 

Sin is a math genius tbh

 

tbh this should be in general discussion tbh.

 

tbh im confused tbh

 

Well, I've only gone up to Algebra II, and to me, it's mostly just a bunch of little things you have to do in the formula. What get's me is the little E sign that's diagonal-shaped. But I do know most of formulas have just variables.