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Lies, Damned Lies and Meaningless Drivel
Posted: 16:56 Sun 14 Sep 2014
by djewesbury
Some posts moved here from The Scottish Independence Referendum, 18th Sept 2014 by jdaw1.
jdaw1 wrote:DRT wrote:That is quite a margin in a two horse race.
Innumerate rubbish.
Odds of 1/4 and 3/1 imply probabilities of 80% and 25% (the total exceeding 100% by the bookies’ profit). So divide by 1.05 to get implied probabilities of 76% and 24%.
Let’s assume that the Yes and No votes are normally distributed, with a standard deviation of ±5% (this σ having been guessed by me). So if the expected outcome were 53.6% : 46.4%, with that uncertainty, the probability of a Yes would indeed be about 76%. But 53.6% : 46.4% is quite a small margin.
Oh, it's suddenly gone very quiet.. Anybody out there…?
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 16:58 Sun 14 Sep 2014
by DRT
djewesbury wrote:jdaw1 wrote:DRT wrote:That is quite a margin in a two horse race.
Innumerate rubbish.
Odds of 1/4 and 3/1 imply probabilities of 80% and 25% (the total exceeding 100% by the bookies’ profit). So divide by 1.05 to get implied probabilities of 76% and 24%.
Let’s assume that the Yes and No votes are normally distributed, with a standard deviation of ±5% (this σ having been guessed by me). So if the expected outcome were 53.6% : 46.4%, with that uncertainty, the probability of a Yes would indeed be about 76%. But 53.6% : 46.4% is quite a small margin.
Oh, it's suddenly gone very quiet.. Anybody out there…?
please define standardly distributed.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:01 Sun 14 Sep 2014
by jdaw1
DRT wrote:please define standardly distributed.
Normally distributed. It’s not, of course, very little is, but the approximation isn’t going to mislead.
If you want to attack, attack the ±5%.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:02 Sun 14 Sep 2014
by PhilW
DRT wrote:please define standardlynormally distributed.
It's exponential.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:04 Sun 14 Sep 2014
by jdaw1
PhilW wrote:DRT wrote:please define standardlynormally distributed.
It's exponential.
For those new to this rant, start
here.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:06 Sun 14 Sep 2014
by PhilW
jdaw1 wrote:Odds of 1/4 and 3/1 imply probabilities of 80% and 25% (the total exceeding 100% by the bookies’ profit). So divide by 1.05 to get implied probabilities of 76% and 24%.
Agreed to there; and that is the margin which surprises me.
I admit that you've then lost me when you proceeded to somehow apply a normal distribution to the voting, since it is a straight yes/no.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:07 Sun 14 Sep 2014
by PhilW
jdaw1 wrote:PhilW wrote:DRT wrote:please define standardlynormally distributed.
It's exponential.
For those new to this rant, start
here.
But for once, it actually is (normal distributions follow an exponential function, unless limited by boundary conditions), and Derek was missing his chance to say so!
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:08 Sun 14 Sep 2014
by jdaw1
PhilW wrote:I admit that you've then lost me when you proceeded to somehow applying a normal distribution to the voting, since it is a straight yes/no.
But our knowledge of the Yes is that it will be μ±σ. By assuming σ, and using the observed probability of 76%, we can deduce μ, which isn’t far from ½.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:10 Sun 14 Sep 2014
by jdaw1
PhilW wrote:But for once, it actually is (normal distributions follow an exponential function, unless limited by boundary conditions), and Derek was missing his chance to say so!
The equation for a normal distribution isn’t exponential, even though it contains an exponential. As you well know.
(Are we off topic?)
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:11 Sun 14 Sep 2014
by DRT
PhilW wrote:jdaw1 wrote:PhilW wrote:DRT wrote:please define standardlynormally distributed.
It's exponential.
For those new to this rant, start
here.
But for once, it actually is (normal distributions follow an exponential function, unless limited by boundary conditions), and Derek was missing his chance to say so!
I didn't want to embarrass him in public.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:15 Sun 14 Sep 2014
by djewesbury
jdaw1 wrote:PhilW wrote:But for once, it actually is (normal distributions follow an exponential function, unless limited by boundary conditions), and Derek was missing his chance to say so!
The equation for a normal distribution isn’t exponential, even though it contains an exponential. As you well know.
(Are we off topic?)
Could an admin please move all this twaddle to Lies, Damned Lies and Meaningless Drivel?
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:18 Sun 14 Sep 2014
by DRT
Please link to the post where you want to make the split.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 17:20 Sun 14 Sep 2014
by djewesbury
DRT wrote:Please link to the post where you want to make the split.
Somebody appears to doing it already. I think the point where mathematicians start discussing bookies' odds is probably a good point to administer the scalpel.
Re: Lies, Damned Lies and Meaningless Drivel
Posted: 17:25 Sun 14 Sep 2014
by jdaw1
Re: Lies, Damned Lies and Meaningless Drivel
Posted: 21:06 Sun 14 Sep 2014
by LGTrotter
Maths is nice. What happened to the link to the maths jokes website? I'm sure there was one.
Re: The Scottish Independence Referendum, 18th Sept 2014
Posted: 09:31 Mon 15 Sep 2014
by PhilW
jdaw1 wrote:(Are we off topic?)
Yes, but it's a good topic.
jdaw1 wrote:PhilW wrote:But for once, it actually is (normal distributions follow an exponential function, unless limited by boundary conditions), and Derek was missing his chance to say so!
The equation for a normal distribution isn’t exponential, even though it contains an exponential. As you well know.
With
σ defined/assumed as a constant, then the normal distribution function is of the form
f(x)=k.eg(x)
Does
g(x) being of quadratic form therefore preclude this equation from being described as of exponential form?
Re: Lies, Damned Lies and Meaningless Drivel
Posted: 09:44 Mon 15 Sep 2014
by flash_uk
LGTrotter wrote:Maths is nice. What happened to the link to the maths jokes website? I'm sure there was one.
Here are a couple of cartoons which made me chuckle
Re: Lies, Damned Lies and Meaningless Drivel
Posted: 09:44 Mon 15 Sep 2014
by flash_uk
and the other