Ok massassi, I need help.
In math, we are doing standard deviations. At the end of the period, my teacher gave us the equation for solving it, and directions to use a calculator to ease the workload. He did not, however, explain what to do with the crunched-numbers in relation to standard deviations. The problem comes with this, because I do not understand the symbols used in the calculator and their relation to the equation.

(some of the symbols are an x with a line over it, a sideways M next to an x, and an o with a tail at the top. Please forgive my crude descriptions, as I said, my teacher did not have time to explain this in relation to the calculator.)

Any help would be much appreciated. Until then, I stand by the statement that standard deviations are the spawn of satan. -_-


(note: I've asked siblings, I have tried google, and I have tried looking up symbols in indexes. But because I do not know the names of the symbols, this makes my job a whole lot harder. Help me, massassi. You are my only hope.)

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Tell me not in mournful numbers, Life is but an empty dream, For the soul is dead that slumbers, and things are not as they seem. Life is real, Life is ernest, the grave is not it's goal; Dust thou art, Dust thou returnest, Was not spoken of the soul.
~William Shakespeare

[This message has been edited by Silent_Rhapsody (edited December 03, 2003).]

1) Should mean the average value for x
2) (Uppercase sigma)Should mean the sum of x
3) Is the symbol for sigma (lowercase)

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Try not, do; or do not.

[This message has been edited by Friend14 (edited December 03, 2003).]

For number 2, what would that sum be? the sum of the entries? or the total number of entries?

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Tell me not in mournful numbers, Life is but an empty dream, For the soul is dead that slumbers, and things are not as they seem. Life is real, Life is ernest, the grave is not it's goal; Dust thou art, Dust thou returnest, Was not spoken of the soul.
~William Shakespeare

Standard deviation is the square root of the sum of the squared deviations from the mean, divided by the sample size minus one. Look at that sentence one bit at a time, it's a lot easier to understand than it sounds.

To get a standard deviation you have to do a lot of little calculations, then put your results from those into one big formula. I trust your teacher gave you the formula, you should be able to figure out how to get everything you need for it pretty easily.

Sideways-M x means the sum of all x's.

Sideways-M xy means the sum of all (x multiplied by y) ie. (x1 . y1) + (x2 . y2) + (x3 . y3) for how however many you have, where . is a multiplication symbol.

Any letter with a bar over it means the mean of that variable. So to to get x-bar, you simply add up all the x's then divide by how many there were.

Sigma (o with a tail of top) is the mathematical symbol for standard deviation.

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The Massassi-Map
There is no spoon.

The equation should look something like this:



The upper case sigma (the E) simply means to plug every value of x into the equation and then add up all the results. n is the number of samples, and x bar is the mean of the data. Lower case sigma is the symbol for standard deviation.

For instance, if you have the values 1,6, and 8, n is 3 and x bar is 5. For every value of x, subtract x bar from x and square the result, then add all the results together: (3-5)^2 + (6-5)^2 + (8-5)^2 = 14. Then divide that by n-1 to get the standard deviation: 14/(n-1) = 14/2 = 7.

[This message has been edited by Argath (edited December 03, 2003).]

/me mad-huggles all
Thank you guys!
<3
One more question, and I'm done. If I were entering the data in to the calculator, and got the 1-Var stats, when it shows the sigma next to x, is that the final solution for the standard deviation?

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Tell me not in mournful numbers, Life is but an empty dream, For the soul is dead that slumbers, and things are not as they seem. Life is real, Life is ernest, the grave is not it's goal; Dust thou art, Dust thou returnest, Was not spoken of the soul.
~William Shakespeare

I am surprised they're letting you use a calculator. In my stats class they made us show all our working out and only use the calculator to add things up.

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The Massassi-Map
There is no spoon.

Methinks Spork is side-stepping the question...

I think it's important to know how to do it on your own. But it makes life a lot easier to use a calculator.

Does anyone know about my question regarding the calculator's 1-Vars stats?

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Tell me not in mournful numbers, Life is but an empty dream, For the soul is dead that slumbers, and things are not as they seem. Life is real, Life is ernest, the grave is not it's goal; Dust thou art, Dust thou returnest, Was not spoken of the soul.
~William Shakespeare

I guess it would depend on the calculator, but presumably, yes, the sigma is the standard deviation.

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The Massassi-Map
There is no spoon.

I would honestly suggest solving it algebraically and using the calculator for finding the final solution (which is undoubtedly what your teacher intended).

When I was in high school, all of our math courses required graphing calculators, although we only ever used them for the arithmetic.

standard deviation.. bleh never did like that

i think with a calculater, you put your calculator into mode 1(not sure how this is on your calc ^^)

then enter the numbers using a comma button or something.. i really can't remember :/

try asking your teacher

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Rah!

Thank you! You guys have been a real help.

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Tell me not in mournful numbers, Life is but an empty dream, For the soul is dead that slumbers, and things are not as they seem. Life is real, Life is ernest, the grave is not it's goal; Dust thou art, Dust thou returnest, Was not spoken of the soul.
~William Shakespeare