Thursday, 10 June 2010

Curly Q

I have a disappointed reader, and we can't be having that. Curly wrote:

I appreciate you taking the time to answer comments left but I do feel somewhat let down by the reply.

My question was number 3. Knowing 34.28% of matches predicted to win by 2 goals did so doesn't really tell us a lot about how successful it is. If the average price obtained was 3.0 after commission then it would be slightly profitable; 2.7 and it would be unprofitable.

I appreciate that you may not have complete figures but it would be interesting to know them if you do.
Here's the best I can do. As I mentioned before, the statistics I kept became more detailed as the season continued, so these numbers are very approximate, with some assumptions being made that may not be true.

In the Premier League, 23.03% of the predicted 2 goal wins finished 2-0. 11.52% won 3-1. The correct score on 2-0 usually paid around 8.0 and on 3-1 about 16.0.

The average price for a home win is hard to say. The nature of the rankings means that when a 2 goal home win is predicted, the match odds price will typically be odds-on. I realised fairly early on, when I saw that the strike rate exceeded expectations, that just backing the win wasn't the most profitable way to play these, which is when I started recalling the results in more detail.

Again I emphasise that these numbers are approximate but in the Premier League, 100 points staked on the 2-0 score would have returned 184, as would 100 on the 3-1 score.

In the other top Leagues, the respective (rounded) returns would have been:

Scottish Premier: 116, 115
Serie A: 114, 182
La Liga: 112, 135
Ligue 1: 107, 214
Bundesliga 1: 76, 114

It will be interesting to see how these games perform next season with more accurate record keeping.

From a second comment, albeit an Anonymous one, it appears there may be a little confusion for some people regarding the purpose of comparing the results of the Elo ratings predictions with the actual results from last season.

He writes:
"39% of games in Scottish Second Division are won by the home team - 50.79% are home wins in the Premier League"

Are won? Were won last season? Were won over the last few season?

Short-term / long-term again my friend.

"Ligue 1 and Scottish Third Division - 57% of matches finish Under. 55% Over in the Conference National and Bundesliga 1."

Another sweeping statement. Presumably based on one season?

These "individual personalities" of different leagues cannot be assumed to be correct on the evidence of such a small sample size. It is certainly correct that the Bundesliga is a high scoring league but that is a fact which can't be proved over one season.
As I thought I had made clear, my observations are from last season and were given to highlight the differences between leagues / divisions and as justification for my decision to look at each league / division individually.

They are not sweeping statements at all. They are the facts from last season.

I’m also not assuming that any league’s “individual personality” is ‘correct’. What does that even mean? How can something of this nature be correct? It is what it is. Different leagues will have different properties and those properties will almost certainly change over time.

Short-term / long-term is a relative term. I could collect league statistics going back to 1888 if I wanted to, but as the data I am comparing it too is from just last season, it seems reasonable to compare like with like.

I am also not interested in trying to "prove" anything - least of all that the Bundesliga 1 is a high scoring league. If next season the Bundesliga 1 is a low scoring league, that’s fine. I really don't care. It’s the relationship with the Elo ratings over that time which is important to me.

What I am interested in is finding any patterns or correlations between the predicted and actual results over a period of time. For now, that period of time is one season. That may be short-term, but it's all I have for now and Roma wasn't built in a day, as we say in Italy.


Anonymous said...

Reading through your blog for the last few days, reminds me of a quote by Winston Churchill- Lies,damn lies and statistics-. Having said that the keeping of records is extremely important for finding an edge.
Looking at the English Premier League and reading various blogs a lot of people seem to be concentrating a lot more on betting/ investing on correct scores, possibly because the 2 -1, 1 - 2 results being historically fairly common.
I certainly agree with the statement that each league has its own characteristic, for example, during the summer,Premier League Clubs will splash out millions on new players. At the start of the season, there will be a lot of high scoring games,as clubs go all out for a win, which will get maximum points. Around November December times, those clubs who have not done so well will review their playing styles and start going more defensive- net result less goals. Then around March time those clubs that are near the relegation area will start to put everything on black going all out for wins obviously resulting in higher scoring games again.
If that scenario does unfold again this season,how would you research your statistics?
Having quoted Churchill, I do think that statistics are an important tool as is a reasonable knowledge of the clubs whose results you are betting on.



Anonymous said...

With regard to your two goal predictions:

I'm a bit confused by your returns on bets on 2-0 and 3-1. 100 units returning 184 suggests, to me, a profit of 84? Not sure if that's what you mean or not. But, if so, then the investments presumably aren't profitable as you would make 84 and lose 100 (assuming level stakes) by covering 2-0 and 3-1.

Of course, you also make no mention of other two goal scorelines which I find a little strange. From previous posts last season, I assume you would also be covering the "unquoted" or has that conveniently been left out because there were no 4-2s or 5-3s? (i don't know if that was the case or not)

Anonymous said...

A team expected to win by two goals can, on average, be expected to win 80% of their games (give or take not very much). 73% isn't a particularly good hit-rate (albeit that your results are relatively short-term).

A major flaw in the way you approach things is that you seem to have no "in betweens". i.e. your methodology works on the simple basis that a team is expected to lose by two, lose by one, draw, win by one, win by two, win by three etc.

With a little work, you could achieve better results if you found a way to incorporate more precise expected (average if you like) supremacy margins a la the spread betting firms.

Curly said...

Thank you for the reply Cassini, I'm sure you'll be pleased to know I've now cheered up.

If I understand you right, you have a 34.28% strike rate on a 2 goal winning margin and an average price of 2.84 (after commission). By my (rounded) maths you would be looking at 2.92 to break even. So, the next question is do these figures not include the unquoted scoreline which you were backing as I recall (a 'lucky' loser in the man city/chelsea match springs to mind) and in which case they may be profitable or have the Elo ratings not actually proved profitable in this market last season?

Once again, thanks for taking the time to reply.