how to get a standard deviation from a set of numbers, simple explanation please.

Question

amistre64 · Answer

hmmm, its variance squared

anonymous · Answer

ya, square root of variance

amistre64 · Answer

find the mean

subtract the mean from all the points and square the results

add up all the results ... and divide by how many there are if its a population, or by one less if its just a sample

amistre64 · Answer

then sqrt that result i think

amistre64 · Answer

var=$$\frac{\sum(x-\bar x)^2}{N(or\ n-1)}$$
right?

amistre64 · Answer

sqrt that to get sd

anonymous · Answer

i don't think its over n

amistre64 · Answer

i wouldnt know, i cant see if you got population or sample

anonymous · Answer

and stand dev is the square root of variance

amistre64 · Answer

the sample has to do with the degrees of freedom i think

amistre64 · Answer

thats the one, sd = sqrt(var)

anonymous · Answer

so, add up all the differences for each value from the mean and square the sum

anonymous · Answer

then....

amistre64 · Answer

add up all the squares of the differences from the mean

amistre64 · Answer

divide it by the correct n or n-1 depending on technical stuff

amistre64 · Answer

then sqrt it

anonymous · Answer

ahhh, ok

amistre64 · Answer

the sqrt at the end is spose to counteract the square at the start.

anonymous · Answer

ok, i can do calc all day, can't stand stats

amistre64 · Answer

stats was fun last semester