Sunday, 1 March 2015

Yields Down When Push Comes To Void

Threads on the Betfair and Blogabet Forums made me realise that some of the the ROI percentages in the FTL are slightly inflated.

I have a faint recollection of this topic coming up early in the season, with the infamous Jonny commenting that:

When ROI is calculated by betting syndicates it is normal practice to exclude void bets
This is correct in my opinion, but bets resulting in a Push are not the same as Void bets.
When a bet is a push, that does not mean that money was not risked – it only means that one gets the stake back after the bet is decided because the match ended in a certain way. It means that this amount of money has 0% yield (or interest) between the time of betting and the time when the stake is returned (it is not available to be invested elsewhere).
The fact that money was at risk is key, and is why Push outcomes should be included in the ROI percentages. When a match is Void, for example due to a postponement, the money was never at risk. Bets on the outcome of an event are conditional upon the event actually taking place!

The next update of the FTL will therefore incorporate this small change. Only seven of the 33 entrants have Push outcomes (Draw No Bet) and the highest percentage is Randolph's, who has just over 10% of his selections ending this way. His ROI% before this weekend was 8.93% under the old method, 7.99% using the new.

I'll actually list both ROI% calculations for a couple of weeks and if anyone has a different opinion about the above change, I'd be interested to hear it, but I think I have it right, albeit a little late.


Tage Poulsen said...

There are some interesting variations on this theme.
On a tennis match you place a negative arbitrage bet at two different bookies.
The underdog is bet at a bookie who only requires 1 ball played.
The favourite is bet at a bookie who requires the match to finish 'normally'
Your profit will of course come when the favourite retires through the match.
This is not a void bet, but it is not a push bet either. How to record this bet?

Another bet type I had great success with 10 years ago.
A very well known UK bookie dipped their toes into MLB betting.
But they treated a baseball match exactly like a soccer match, that is, the odds stood even after a change of pitcher.
So place a bet on a big favourite at a bookie who voids the bet in case of a pitcher change and the arbitrage bet on the dog at the UK bookie.
This situation is a possible 'half void' bet. How to record this?

Brian H said...

Interesting one Cassini. I originally included void bets in the ROI calculation on my TipsterTable but I changed when I read what you said on your site.

My thinking before then was that they should be included because the money was 'invested' without a return. Even if the money was never at risk due to a postponement, another potentially profitable investment may have been missed.

In most cases it will make little difference however and as long as the methods used are clear and consistent then I think either is acceptable.