Friday, 27 March 2015

DC v UR v Sq

A couple of comments on my proposal to modify the formulae for Lay bets. Marty was straight to the point:

I object to revising the settlement of lay bets
Well, fair enough, although I’m not sure what FTL entry (if any) Marty is voting on behalf of.

Jamie A, who actually IS an entry, suggested an alternative approach (I’ll call it the Under-Round):
So back bets have a 2% margin and lay bets have 4%!
I would understand making the lay bets have a higher margin for the rest of the season since they had a lower margin for the season to date - but the fairest way is still:
Pinnacle back price * (pinnacle margin)^2 = lay price
Then lay and back markets have the same margin.
While Jamie’s formula is solid enough, it seems to me that this would be ideal if the back prices they are derived from are Exchange prices, but they are not, since we don’t have Exchange prices available.

Using the Double Chance [DC]  formula means using actual, and verifiable, prices so I still prefer my Double Chance approach for a couple of reasons.

The first is that a Lay bet is nothing fancy or mysterious, it is simply a convenient way of backing all other possible winners in the market. In a binary event, a Lay of A is a Back of B. Lay Federer / Back Djokovic – it’s the same bet.

Football has its pesky Draw, but a Lay of H is still simply a Back of both D and A. Using the DC is merely splitting the one Lay bet into two Back bets. Joseph Buchdahl suggested using the +/- 0.5 prices which would indeed be the perfect (except for Draw lays) answer here, but those prices are not available, at least not where the Match Odds Pinnacle Sports Prices are available, and where I need them.

The second reason is that this method is directly using prices that are extracted, and are available on the web site.

Although the FTL is intended to be more for comparison purposes (hence the use of one book’s prices rather than the best), the Double Chance method does more closely reflect the real world experience.

The differences are small anyway. A lay at around the 2.0 mark, and the DC formula records a profit of ~0.93 as does Jamie’s UR method. At shorter prices, the DC method is slightly higher (a lay at 1.65 for example returns ~1.41 rather than ~1.39) while at higher prices, the UR returns are slightly higher (a lay at 2.4 for example returns ~0.66 for the DC, ~0.67 for the UR).

So, FTL entrants, we have three options:
  1. Leave the method as it is today - Status Quo (Sq)
  2. Use the Double Chance formula
  3. Use the Under-Round formula
Since this is a quiet weekend, feel free to submit your votes with your entries before the April 4th round. April already! 

To satisfy my own curiosity, I ran the DC formula numbers for the Bundeslayga since 2012-13 (the first season that Pinnacle Sports prices are reported), and they show a profit of 4.33 points from 258 selections. 

As I have been saying since at least 2013 about the Bundeslayga:
It's proven profitable for several seasons, and used more as a Premium Charge mitigation system than one that will make me rich.
An ROI of a verifiable minimum 1.68% (Pinnacle Sports match odds can usually be beaten) may not be exciting or glamorous, but if you are either paying, or may be paying in the future, the Premium Charge, methods like this are very useful. (I suspect any critics are currently exempt from this charge). The rules used for this verification were Home team between 1.3 and 2.0 inclusive on Pinnacle Sport. 1.3 to 1.39 inclusive would have been a higher ROI%, but then I am stupid.
Although Tage may well be the most brilliant statistician to come out of Aarhus, (why do I always want to sing "in the middle of our street" when I hear that name?), I'm not sure he would score so highly on the arguably more important Emotional Intelligence scale.

As the input from the rather more polite Jamie shows, there is no 'correct or wrong' answer to the question. In the absence of a +/- 0.5 price, the Lay profit needs to be derived. The original Lay rules were based on real-life experience for a Friendly competition, were made clear from the start, and apply to everyone.

Anyway, the Double Chance and Under-Round methods are both fine with me, and I'll go with whichever receives the most votes.
Very well put FT member Daily25. Please vote! Steve's blog is one of the best out there, in large part because of his positive attitude even when things aren't going well.
It seems that a lot of the services Steve uses are having bad runs right now. It happens.

Too many people are only too quick to assume the worst and jump to (usually wrong) conclusions. Or they put 2 and 2 together and come up with 5 (not Tage - he's a retired statistician). And an argument over in-play trading versus pre-game betting is ultimately pointless since it's a personal preference. For some sports, trading is (in my opinion) the only way to be profitable long-term. For others, where in-play has little liquidity, the value is (in my opinion) likely to be pre-game. If you're making a profit, excellent. It doesn't mean that others are not, and more than one style can be profitable at the same time. They are not mutually exclusive. Your results are not improved by wasting time finding fault with the approach of others; in fact if that time were spent on fine-tuning your own methods, your results might well be improved. Betting is all about opinions - if we all had the same opinion about everything, there'd be no market - but the debate over opinions should at least be civil and criticisms constructive.

A puzzle, courtesy of @DavidJBodycombe :


Mark Iverson said...


Marty said...

I represent (the esteemed) Randolph and Mortimer. Also I have a childl-like brain since that puzzle was easy (and fun).

What are the rules for today's entries?

I vote:
1, 3, 2