What are the chances of that?

The sport of kings.
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guy333
Posts: 61
Joined: Sun Aug 16, 2015 9:47 am

If you are betting on short priced favourites between 1.4 and 1.8 and you find youself on a winning streak, at what point can you conclude that your winning streak is down to an edge rather than random chance?

As the circumstances I need only happens 3 or 4 times a day it is taking quite a while to test my theory but at the moment I have 8 wins on the "trot" and no losses.

Can this be luck or should I put the champagne on ice?
marko236
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Joined: Fri Jul 12, 2013 11:54 am

If your getting the same results after a thousand races it probably is a good stratagy. But as i'v found good stratagies dont last forever you may have to change it a little now and again.
PeterLe
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Joined: Wed Apr 15, 2009 3:19 pm

Hard to say.
I have a system that has traded just over 8000 markets and Im still not sure if it is a winning system. (looking good though!)
Id put the Champagne away for the time being if I were you!
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gazuty
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PeterLe
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Gazuty
Thanks for that.
I saw that link before my holidays and intended checking it out..

What did you use for the Prob of a single trial?
For EG; Assume you were only laying and only ever offered a price at reverse odds. Further assume that there was always a gap between prices
EG Lay at 2 (Current Lay price = 2.3)

Or would you use the strike rate: EG I was sucessfull x% of the time? Eg Sucessfull 1 in 3 races, ie 0.333
Thanks
regards
Peter
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gazuty
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PeterLe wrote:Gazuty
Thanks for that.
I saw that link before my holidays and intended checking it out..

What did you use for the Prob of a single trial?
For EG; Assume you were only laying and only ever offered a price at reverse odds. Further assume that there was always a gap between prices
EG Lay at 2 (Current Lay price = 2.3)

Or would you use the strike rate: EG I was sucessfull x% of the time? Eg Sucessfull 1 in 3 races, ie 0.333
Thanks
regards
Peter
(Editing.) If you have done enough trials of a strategy - strike rate of the strategy.

If you were doing a single lay at 2 in an efficient market (back/lay book @ 110.1/99.9) then I'd say the probability is 0.5.
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gazuty
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guy333 wrote:If you are betting on short priced favourites between 1.4 and 1.8 and you find youself on a winning streak, at what point can you conclude that your winning streak is down to an edge rather than random chance?

As the circumstances I need only happens 3 or 4 times a day it is taking quite a while to test my theory but at the moment I have 8 wins on the "trot" and no losses.

Can this be luck or should I put the champagne on ice?
Ok. Just for arguments sake let's say you are backing at an average of 1.6.

Efficient market says your probability of winning is 0.625.

8 trials @ 0.625 for 8 successes. Probability = 0.023 ie 2.3%

Not small enough to prove an edge.

Come back once you've done 100 trials.

What would we expect? 63 wins and 37 losses. Let's be modest.

£10 stakes. Wins 63 X £6 X 0.95 = 359.1. Losses 37 X £10 = 370

Expected outcome -£10.90

What would the probability be in 100 events of getting 70 or more wins? 7.2%

Scale up to 1000 events

What would be the probability of getting 700 or more wins @ 0.625 probability? 0.0001%

So if you can do that on 1000 events you have an edge (and my respect) and you can uncork the champagne.
PeterLe
Posts: 3727
Joined: Wed Apr 15, 2009 3:19 pm

gazuty wrote:
PeterLe wrote:Gazuty
Thanks for that.
I saw that link before my holidays and intended checking it out..

What did you use for the Prob of a single trial?
For EG; Assume you were only laying and only ever offered a price at reverse odds. Further assume that there was always a gap between prices
EG Lay at 2 (Current Lay price = 2.3)

Or would you use the strike rate: EG I was sucessfull x% of the time? Eg Sucessfull 1 in 3 races, ie 0.333
Thanks
regards
Peter
(Editing.) If you have done enough trials of a strategy - strike rate of the strategy.

If you were doing a single lay at 2 in an efficient market (back/lay book @ 110.1/99.9) then I'd say the probability is 0.5.
Ok thanks
Number of Trials: 9674
Successes : 1747
Strike : 18.06
Therefore Cumulative Probability : 0.505

I wasnt going to post this but I thought it worthwhile ilustrating the graph. (it also fits in the general theme of Peter's rcent post)...Might help someone new to this type of thing..?

This strategy was based on a hunch. You can see from the graph that it didnt fair too well initially (but I was almost certain it would work long term).

After I had a relative amount of data, I extracted the bet history to Excel, and created a Pivot to see what was working and what wasnt. I removed the negative going forward. After than there was an initial surge in profits, but then it started to stall.

Rinse Repeat the data Extraction/Pivot etc
Im fairly sure this will work long term, so much so, I've now started to compund the profits by increasing the stakes by a tiny fraction.

Projections based on compounding are frigtening! Been here many times before, so we will have to see!

Anyway thanks for input Gazuty
Regards
Peter
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gazuty
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Well done Peter. Crack open the bolly.
guy333
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Joined: Sun Aug 16, 2015 9:47 am

Meanwhile back on the original question.

It seems that it doesn't matter how successful a system is in practice mode it will inevitably fail when the real money enters the stage.

Got to 18 wins out of 21 races which I thought was a reasonable success rate but as soon as I went into live mode I lost 2 in a row.

What are the chances of that ????

Still 18 out of 23 is still pretty good so I am not going to abandon ship straightaway, so frustrating though.
poklius
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Joined: Sun May 17, 2009 11:58 am

guy333 wrote: Got to 18 wins out of 21 races which I thought was a reasonable success rate but as soon as I went into live mode I lost 2 in a row.
21 races is nothing, you need at least couple of thousand spread across different seasons to make any conclusions
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