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#1
02-20-2005, 12:00 PM
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GTOT HELP
Page 180 dangerous idea 11:
Expectation= 30/hr Standard deviation= 500/hr Playing session=5hrs Computing the chance of a loss after a five hour playing session is solved by the following equation: 0 = (30)(5)+(x)(500)(5^.5) x= -0.13 Using a normal distribution table -.13 standard deviations corresponds to 44.83 percentage point. Therefore about 45 percent of your 5 hour playing sessions will result in a loss. So far so good. Heres where i get lost. "your median loss will occur at the 22.815 percentage point" Can someone break down the math that gets the answer 22.815 I don't have a statistics background and my common sense makes me think the answer is half of 44.83 which is 22.415 I know Mason's number is not a typo because he used it in subsequent calculations, so how did he arrive at it? Thank-you 
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#2
02-20-2005, 03:08 PM
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Re: GTOT HELP
[ QUOTE ]
Page 180 dangerous idea 11: Expectation= 30/hr Standard deviation= 500/hr Playing session=5hrs Computing the chance of a loss after a five hour playing session is solved by the following equation: 0 = (30)(5)+(x)(500)(5^.5) x= -0.13 Using a normal distribution table -.13 standard deviations corresponds to 44.83 percentage point. Therefore about 45 percent of your 5 hour playing sessions will result in a loss. So far so good. Heres where i get lost. "your median loss will occur at the 22.815 percentage point" Can someone break down the math that gets the answer 22.815 I don't have a statistics background and my common sense makes me think the answer is half of 44.83 which is 22.415 I know Mason's number is not a typo because he used it in subsequent calculations, so how did he arrive at it? Thank-you [/ QUOTE ] You are correct, and it is just a typo. Your median loss is the loss for which half your losses are higher and half are lower. If you lose 44.83% of the time, then half of 44.83% or 22.415% of the time you will have a loss lower than this, and 22.415% of the time you will have a loss higher than this, so 22.415% is where your median loss occurs. If you don't round off, the 0.13 standard deviations becomes 0.134 standard deviations, and you lose 44.66% of the time, and your median loss is actually 22.33%. The only subsequent calculation I see affected is that the number of standard deviations used to compute the median loss should be 0.76 standard deviations instead of 0.74 standard deviations. I'll inform Mason of this post.
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#3
02-20-2005, 03:29 PM
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Re: GTOT HELP
[ QUOTE ]
The only subsequent calculation I see affected is that the number of standard deviations used to compute the median loss should be 0.76 standard deviations instead of 0.74 standard deviations. [/ QUOTE ] That's what I was referring to. Thanks Bruce your the best.
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