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math guys: how does one figure out a standard deviation

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  • math guys: how does one figure out a standard deviation

    it's been ages since i've had to use this, but i was wondering how to apply this to a game we play that involves rolling many, many dice.
    I wasn't born with enough middle fingers.
    [Brandon Roderick? You mean Brock's Toadie?][Hanged from Yggdrasil]

  • #2
    1. excel
    2. stdev([cell range])
    "The issue is there are still many people out there that use religion as a crutch for bigotry and hate. Like Ben."
    Ben Kenobi: "That means I'm doing something right. "

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    • #3
      unfortunately i don't have access to a laptop when i'm playing a game. i need to be able to figure out if a set of rolls is within one or not more or less on the fly.
      I wasn't born with enough middle fingers.
      [Brandon Roderick? You mean Brock's Toadie?][Hanged from Yggdrasil]

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      • #4
        find the mean
        then find the variance
        then take the square root of the variance.
        "Everything for the State, nothing against the State, nothing outside the State" - Benito Mussolini

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        • #5
          i dont see how you can apply this to a game of rolling the dice many times. since the expected value of each roll is 3.5, an infinite number of rolls will lead to a standard deviation of zero (by Central Limit Theorem)
          similarly, a large number of rolls (say 100) will also get you a standard deviation that will approach zero (by Law of Large Numbers)
          "Everything for the State, nothing against the State, nothing outside the State" - Benito Mussolini

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          • #6
            The population standard deviation can be simply calculated as follows:

            1) sum all values
            2) sum the squares of all values
            3) square the result from (1)
            4) Divide (3) by N (the number of values)
            5) Subtract (4) from (2)
            6) Divide (5) by N
            7) Take the square root of (6)

            So, if we have 3, 6, and 7 as values:

            1) = 3+6+7 = 16
            2) = 9 + 36 + 49 = 94
            3) = 16*16 = 256
            4) = 256/3 = 85.33
            5) = 94 - 85.33 = 8.67
            6) = 8.67/3 = 2.89
            7) = SQRT(2.89) = 1.7
            12-17-10 Mohamed Bouazizi NEVER FORGET
            Stadtluft Macht Frei
            Killing it is the new killing it
            Ultima Ratio Regum

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            • #7
              Originally posted by Lawrence of Arabia
              i dont see how you can apply this to a game of rolling the dice many times. since the expected value of each roll is 3.5, an infinite number of rolls will lead to a standard deviation of zero (by Central Limit Theorem)
              Uhhhh....no
              12-17-10 Mohamed Bouazizi NEVER FORGET
              Stadtluft Macht Frei
              Killing it is the new killing it
              Ultima Ratio Regum

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              • #8
                uuuuh yeah.

                SE = Stdev/sqrt(n)
                "Everything for the State, nothing against the State, nothing outside the State" - Benito Mussolini

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                • #9
                  Would you like to make any more absurd statements about basic statistical concepts, Lawrence?
                  12-17-10 Mohamed Bouazizi NEVER FORGET
                  Stadtluft Macht Frei
                  Killing it is the new killing it
                  Ultima Ratio Regum

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                  • #10
                    Originally posted by Lawrence of Arabia
                    uuuuh yeah.

                    SE = Stdev/sqrt(n)
                    You must be an idiot...
                    12-17-10 Mohamed Bouazizi NEVER FORGET
                    Stadtluft Macht Frei
                    Killing it is the new killing it
                    Ultima Ratio Regum

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                    • #11
                      must be . . .
                      "Everything for the State, nothing against the State, nothing outside the State" - Benito Mussolini

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                      • #12
                        oh, one more thing. you proved my point in your previous post

                        6) Divide (5) by N
                        7) Take the square root of (6)

                        what happens when n=100. when n= 1000? when n= 10000

                        "Everything for the State, nothing against the State, nothing outside the State" - Benito Mussolini

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                        • #13
                          Let's make this absolutely clear: you are claiming that the standard deviation of any set of independent dice rolls approaches 0 as the size of the set approaches infinity?
                          12-17-10 Mohamed Bouazizi NEVER FORGET
                          Stadtluft Macht Frei
                          Killing it is the new killing it
                          Ultima Ratio Regum

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                          • #14
                            Originally posted by Lawrence of Arabia
                            oh, one more thing. you proved my point in your previous post

                            6) Divide (5) by N
                            7) Take the square root of (6)

                            what happens when n=100. when n= 1000? when n= 10000

                            What happens is that the difference in the sums grows linearly, you idiot.
                            12-17-10 Mohamed Bouazizi NEVER FORGET
                            Stadtluft Macht Frei
                            Killing it is the new killing it
                            Ultima Ratio Regum

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                            • #15
                              Do all economists receive such a poor education in statistics, or are you particularly dimwitted?
                              12-17-10 Mohamed Bouazizi NEVER FORGET
                              Stadtluft Macht Frei
                              Killing it is the new killing it
                              Ultima Ratio Regum

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