munday

http://forums.corvetteforum.com/zerothread?id=789039

thanks


[Modified by munday, 9:32 PM 3/31/2004]

Double Aught

Sorry, got a headache just looking at the pics. :banghead:

stpman

I think you got the answers in the other thread but I think that i=1 means you increase the value of x by 1 1,2,3...... if i=2 2,4,6

But it has been a Looooooong time since I've done any of that.

Steve :steering:

wugak

MS Excel baby!!!!!!!

stdev(range) works just great!!!

wugak

OK for real maybe I can help. If you are really stuck then post back or email me at work at tdifinizio@staplausa.com and I will give you my phone number.

Standard deviation is the average of how far you are from the average. "What is your average deviation from the average".

The big giant E symbol is a sum like others said. In order to process the equation you need to do a bunch of little calculations. Say you have a group of 10 numbers and you want the std dev.

Calculate the average of the 10 numbers, then hold onto that number.

Now take each of the 10 numbers one at a time and subtract the average from each number. The little i means if you have 10 numbers in the group you have to do this 10 times.

Square each of those numbers. This is done mostly to get rid of the negative numbers you got.

Now add up all the 10 numbers you got above. That's the sum part, the big E.

Now divide that by the number of values you had, which is 10.

Then take a square root and voila.

Like I said, cheat a bit and do the individual calculations in excel or an HP calculator.

Was that any help at all?
Tony :crazy:

NHvette

The i=1 is simply the start of the summation. There should be a terminal
value of i at the top of the summation symbol. Also, it sounds like a typo,
where it should be n=1 at the bottom of the symbol.

The symbol basically says "add up all the values after the symbol when
substituting n=1,n=2,n=3 ... n=N".

Hope this helps.

Hey Tony ... right down here in Burlington. :seeya

wugak

True! Also there are 2 equations there. I believe the one with N on the bottom is for a sample size of 32 or more, the N-1 is for small samples. For various weird math reasons the stdev formula chokes on samples of less that 32 values.

Up here is Tewksbury!!!

I'm just a lurker with a C3 on my mind, I don't own one......yet :cheers:

2TONE82

...but she needs to learn this stuff 'cause she will use it every day...ya, that's what they told me and that's what I tell my kids.... :U

Sorry, hope you got the help she needed. I took a big ole brain dump when I finished stats!! :lol:

munday

she aced her test...thanks guys/gals, ya'll helped a whole lot!!!!!