Question

How do I derive computational formula for standard deviation from definition using elementary algebra?

Answer 1

statistical standard deviation from elementary algebra? HA!!

Answer 2

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Answer 3

standard deviation in simplest terms is just the average distance stuff is from the mean

Answer 4

so would it just be square root of sum of means divided by n?

Answer 5

for a population yes; that is a good assessment

Answer 6

hmm seems too easy haha

Answer 7

sum of the distances from the mean for every data point

Answer 8

http://www.answers.com/topic/standard-deviation

Answer 9

the distance is squared to get positive values to sum up and then is divided by the number in the population and square rooted to account for the squaring to begin with

Answer 10

when playing with samples you run into degrees of freedom and other adjustments :)

Answer 11

I'm confused....how would i write this as an equation other than how standard deviation is usually expressed?

Answer 12

have you tried using celtic runes? :)

Answer 13

no what is that

Answer 14

its chicken scratch that the norsemen used to write in lol

Answer 15

\[\sigma=\sqrt{\frac{\sum{(x-\bar x)^2}}{N}}\]

Answer 16

xbar should be mu tho :)

\[\bar x = \mu\]

Answer 17

yaa thats the formula I am familiar with, but I am supposed to find another way to write it using algebra I guess...its an extra credit question

Answer 18

all algebra is moves things around

Answer 19

\[\sigma^2(N)=\sum(x-\mu)^2\]
maybe?

Answer 20

hmm its worth try haha

Answer 21

thanks!

Answer 22

good luck with it :)

Answer 23

thank you!

Answer 24

I am supose to do the same thing and this does not sound right

Answer 25

are you in stats summer school ivc??

Answer 26

yeah

Answer 27

well you're in my class then. ya i don't get what he is looking for..

Answer 28

As I asked for Frodolokalike same question, what definition were you given in class?

Answer 29

just the one in the book, but i think computational formula means what you would input into your calculator...

Answer 30

I think that's what computational formula means as well (or into a computer).

I mean its very straightforward if you just have a small population or sample.

Was the definition in the book "square root of variance"?

Answer 31

yaa that or it gave you the equation sum of (x-mean)^2 all divided by 2

Answer 32

so the computational formula for variance is here http://en.wikipedia.org/wiki/Variance#Computational_formula ....maybe you could just square that

Answer 33

i think its s= variance ^2

Answer 34

oh jk its not

Answer 35

variance is s^2

Answer 36

the computational formula is the formula in the book is labeled formula 3-5

Answer 37

oh i see it...so would that be the answer? seems too easy hah

Answer 38

i dont think it is... he wants us to define the forumula using elementary algebra

Answer 39

I think you have already done part of it above....

sqrt(variance), so what's variance? Plug that in. Whats expected value? plug that in....

Answer 40

I'm so lost

Answer 41

it almost sounds like a poof like heres the answer figure out how to get that answer using algebra

Answer 42

yaa I have asked a few people already and still can't figure it out

Answer 43

I think between you, you can come up with an answer to this question.
Sleep on it.

Answer 44

its due tomarrow at 11

Answer 45

Have a look at the first section, Basic examples, of

http://en.wikipedia.org/wiki/Standard_deviation

See if that gives you any ideas.

Answer 46

sarah91 have u had any progress

Answer 47

not really I if I dont find anything better I'm just going to write the computational formula to find variance and take the square root of it