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[jman5581]

Way to go Dunbar.. you're rollin' now.

[jman5581]

Just finished all my law school finals, so I've got time back on my hands...

dunbar, about a month ago you wrote... "I've got to catch a plane in a few hours, but at some point I'd like to write some more about the statistical significance of jman's results."

I'd be interested in hearing what it is you have to say.

[Dunbar]

Originally Posted by jman5581

Way to go Dunbar.. you're rollin' now.

I'm rippin'. At my current rate of one pick every 2.5 months, I'll finish my first round of 10 in about August 2009, unless I pick a clunker and have to reset. Stay tuned. ;>)

Originally Posted by jman5581

Just finished all my law school finals, so I've got time back on my hands...

dunbar, about a month ago you wrote... "I've got to catch a plane in a few hours, but at some point I'd like to write some more about the statistical significance of jman's results."

I'd be interested in hearing what it is you have to say.

hmmm. Oddly, it's going to probably take until my next flight before I have time to look at it again. But I'm glad you reminded me.

What I want to be able to say is something like, "there's just an 10% chance that jman is betting with worse than a 5% disadvantage." To do that, I need to calculate the standard deviation of your set of bets. It's easy, but like many easy things, it'll probably take an hour or 3 before I set it up right.

btw, the hypothetical quote above may not sound very impressive, but there are very few cappers who would be able to claim that level of success from a set of well-monitored picks .

--Dunbar

[jman5581]

let's see... only a 10% chance that I'm betting with a 5% disadvantage... eek, I'm already in over my head... but I think I'm sounding pretty smart... in that case, I will not argue with you.

[Dunbar]

Originally Posted by jman5581

Just finished all my law school finals, so I've got time back on my hands...

dunbar, about a month ago you wrote... "I've got to catch a plane in a few hours, but at some point I'd like to write some more about the statistical significance of jman's results."

I'd be interested in hearing what it is you have to say.

jman, I finally got around to looking at this again. Let me see if I can produce some statistics without (1) making a mistake, or (2) putting you to sleep.

Here's what I did:

1. I calculated the average result of your 119 show bets. You lost an average of $0.008 per $2 show bet.

2. I calculated the standard deviation of your 119 show bets. The standard deviation is 0.94, based on $2 bets.*

3. I calculated the "standard error", which is the standard deviation divided by the square root of the number of bets. 0.94/sqrt(119) = 0.09.

Armed with this data, the challenge is to tell whether your good performance was just a matter of luck. (like a roulette player who just happens to hit a few numbers.)

Consider these two "tests":

Test 1: Can we distinguish jman's record from someone who loses at the track take, say 16%?

A -16% bettor would lose $0.32 per bet compared to jman's $0.008. A 32 cent loss is more than 3 standard errors worse than jman's loss. A 3-standard error result should occur by luck in about one in 700 cases. I think we can assume that jman's picks were clearly better than the track take.

Test 2: Can we distinguish jman from someone who picks well enough to lose at just 5%?

A -5% capper would lose $0.10 per $2 bet. That's about $0.09 worse than jman's result. The difference between a -5% capper and jman result for his 119 bets is about one standard error. That kind of difference occurs by luck about 1 time in 6. We can't really rule out the luck element at that level.

Bottom Line: Your picks clearly showed that the difference between your results and a dart-thrower is statistically significant. But we'd need more picks to say that you're doing better (in a statistically significant sense) than a capper who has a 5% average loss.

Bottom Line, version 2: There's less than 1 chance in 700 that a dart-throwing capper could have produced results as good as yours. There's about 1 chance in 6 that a capper who averages a 5% loss could have produced results as good as yours over the course of 119 bets.

--Dunbar

* one easy way to do this is use the Excel function, =STDEVA(C1:C119), where the payoffs are in cells C1 down to C119.
.

[jman5581]

Well, there you have it folks... thanks Dunbar! We make a great team, I do all the fun part and you do all the grunt work because a) I'm too lazy and/or b) inept. Thanks for helping out with the experiment and good luck on your picks.

[Rupert Pupkin]

Originally Posted by Dunbar

jman, I finally got around to looking at this again. Let me see if I can produce some statistics without (1) making a mistake, or (2) putting you to sleep.

Here's what I did:

1. I calculated the average result of your 119 show bets. You lost an average of $0.008 per $2 show bet.

2. I calculated the standard deviation of your 119 show bets. The standard deviation is 0.94, based on $2 bets.*

3. I calculated the "standard error", which is the standard deviation divided by the square root of the number of bets. 0.94/sqrt(119) = 0.09.

Armed with this data, the challenge is to tell whether your good performance was just a matter of luck. (like a roulette player who just happens to hit a few numbers.)

Consider these two "tests":

Test 1: Can we distinguish jman's record from someone who loses at the track take, say 16%?

A -16% bettor would lose $0.32 per bet compared to jman's $0.008. A 32 cent loss is more than 3 standard errors worse than jman's loss. A 3-standard error result should occur by luck in about one in 700 cases. I think we can assume that jman's picks were clearly better than the track take.

Test 2: Can we distinguish jman from someone who picks well enough to lose at just 5%?

A -5% capper would lose $0.10 per $2 bet. That's about $0.09 worse than jman's result. The difference between a -5% capper and jman result for his 119 bets is about one standard error. That kind of difference occurs by luck about 1 time in 6. We can't really rule out the luck element at that level.

Bottom Line: Your picks clearly showed that the difference between your results and a dart-thrower is statistically significant. But we'd need more picks to say that you're doing better (in a statistically significant sense) than a capper who has a 5% average loss.

Bottom Line, version 2: There's less than 1 chance in 700 that a dart-throwing capper could have produced results as good as yours. There's about 1 chance in 6 that a capper who averages a 5% loss could have produced results as good as yours over the course of 119 bets.

--Dunbar

* one easy way to do this is use the Excel function, =STDEVA(C1:C119), where the payoffs are in cells C1 down to C119.
.

Excellent work as always Dunbar!

[dalakhani]

This is absolutely one of the most informative threads i have read on this or any other website.

Thank you Jman and Dunbar!!! Cheers to the both of you!

[Dunbar]

Dalakhani and Rupert, thanks for the nice comments!

--Dunbar