Wednesday, 4 March 2015

Pushing On

Tage comments further on the Push / Void discussion:
As my comment clearly shows I’m of course aware that I place two distinct bets in the situations I describe.
My answer was to the question posed by Tage which was "How to record this bet?"  This bet, not 'these bets'. My answer was that his examples were those of two bets.
And I agree with you that if ROI is the only purpose of a betting record your method is flawless.
I don't believe that I have ever suggested ROI is the only purpose of a betting record. I would suggest that ROI is something of a peripheral statistic to be used with extreme caution.
But I actually use my own and tipsters betting records for many other purposes. 
Presumably you know exactly how the ROI numbers are calculated. As the threads and comments have shown, there are different opinions on this.
And I see problems with your method.
Conceptually I do in fact regard a surebet as one bet.
How else can I place two 10k bets with a 2k betting bank?
A betting bank is also conceptual, and as I will come too later, 'sure bets' have a tendency to not be so sure.
Most exchanges are smart enough to calculate the amount available to bet. So it’s possible to trade a golf tournament for 100k starting with 5k.
I doubt you record the 150 single bets on a golf market separately, and if you do I can’t imagine how the profit/loss on each bet should be recorded.
How one records the 150 single bets is up to the person placing them, but each bet SHOULD be recorded.

Serious investors should record all their bets, although grouping say 50 losing bets with the same book into one for convenience isn't a big deal.  
For statistical purposes a betting record with arbitrages is dangerous using your method.
A tipster has 100 bets in Denmark Superliga with a ROI of 3%.
I don’t see evidence of this tipster having an edge betting the Superliga if all 100 bets are parts of surebets.
What is dangerous here is someone giving the ROI% any value after just 100 bets! As the FTL has shown this season, entries have gone on runs, both good and bad, and 100 is too small a sample.

If a tipster's strategy involves arbitrage, surely this would be made evident?
I (mistakenly) thought you would agree that the simple method you describe is only useful in simple situations.
I went up a level and described what I called ‘a negative arbitrage bet’.
Using the definition of a surebet there is a guaranteed profit. Not here. There will in most cases be a loss. The profit occurs in case of a PUSH or a VOID. As your article was about PUSH and VOID bets I offered these examples.
My post was written to cover binary or football bets, and how best to record them and have an accurate, if not necessarily very useful, ROI%.

For conceptual 'surebets' where the risk is zero, ROI is meaningless (although whether or not the risk is ever really zero is arguable given that you might not necessarily get your money back once invested. Sportsbooks folding is hardly a rare occurrence, and there are other risks such as losing out to the 'palpable error' rule).

If I were forced to come up with an ROI% for these, I would personally record the individual bets and combine the bottom lines, but make it clear to any third-parties how the figure is calculated.
Back to the usefulness of ROI, and it is something that Steve at Daily 25 keeps track of:
Long run, most of us would be ecstatic with an ROI of 5%, and more than happy with a 1 - 2% net return.

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