Sunday, 19 May 2019

Cassini's Law

There's a law known as "Cassini's Law", which states that the moment you start talking about a long winning sequence, along comes a loser. Or in this case two.

The T-Bone System ended its winning run at 13, a number not renowned for being associated with good fortune, with not one, but two losses on Friday, which takes the profit on the basic systems down to 9.25 and 8.60 points on the Straight Up and Run Line respectively.

Results for May to level stakes so far:

Meanwhile in the NBA Playoffs, the strategy of backing Unders is profitable so far. 

The logic I use here is that in the playoffs, the total in Eastern Conference games over the last ten seasons is six points fewer per game than in the regular seas, while in the Western Conference, the drop in points is 2.51. 

However, weighting so that recent seasons are more impactful, and the averages are 4.61 and 1.58 points per game.

This season, the regular season average total for Eastern Conference games was 219.7 points, so backing the Unders in games where the line is around 215 points or higher should be unpopular with the public, and thus offer value to the sharper bettor. Likewise in the West, the total where the squares balk should be around 222 points.

So far, we have a 10-7 record in the East, while in the Western Conference, we have a 5-2 record. A 15-9 record is a 22% ROI, but with so few matches in the playoffs, be wary of some variance with this idea.     

And with that, I leave you for a week. I'm off to Las Vegas shortly at work's expense for a different type of conference, but hoping to find a few hours to play some Craps and watch some games. Craps may have a -EV, (1.36% or less if playing optimally and taking the odds), but it's a lot of fun, a very social game, and after a big win a few years ago, I'm still in lifetime profit. Not to mention the free drinks, meals and rooms they will offer you after a long session.

A hot roll at the Craps table is like a winning sequence on a sports system. You want to keep pressing, but know at some point the 7 will show up. 

Friday, 17 May 2019

Repetition Compulsion

A thread appeared on my Twitter timeline on the topic of whether someone can be so bad at betting that money can be made by fading (opposing) their selections.

It's an idea I remember reading about years ago. The argument was that in betting, even negative information is useful.

Just a couple of months ago, I wrote that:

Given that my grandmother would be expected to pick winners at a rate of around 50%, and she's been dead for over 30 years, this didn't seem to be a hugely impossible task.
The fact is that when you are betting on coin-toss events, picking your selections at random means you should break even over the long term, excluding commission of course, which is what ultimately beats most bettors.

Losing intentionally is as hard as winning, as anyone who has tried arbitrage betting with the intent to lose on Betfair and win elsewhere to avoid Premium Charges, will be able to confirm. Well, anyone except Tony Hargraves, for whom the laws of probability apparently conveniently suspend themselves in this regard.

While many people, some successfully, put in a great deal of effort to find value, enough to beat the odds and commission, and become profitable over the long term, it's not clear why anyone would make such an effort to intentionally lose.

As the always interesting @RufusPeabody wrote:
The idea that there are people so bad at betting that fading them — betting the opposite of what they’re on — provides value is preposterous. Yes, the average bettor is worse than a coin flipper (I’d guess like 49.7%) because of biases that they fall victim to, but not by much.
Think about it logically — what talent could someone (ostensibly trying to win) have for picking losers? Where is that skill coming from? And what does that say about the efficiency of the market if that’s possible?
@JFCPicks contributed to the debate that:
Overreacting to recent results is the only thing I can think of that's liable to result in long-term losing. Theoretically, it should be just as hard (if not harder) to lose consistently betting -110 than it is to win consistently betting -110.
Indeed. While this bias should be self-correcting, in my experience there are several markets where it is not. The success of the T-Bone System is based on this bias. 

Profitable, so-called 'revenge', systems aren't successful because the team tries that little bit harder next time out. Their success is because the market is inefficient, the inefficiency due to the aforementioned overreaction by the betting public, and thus the market, to recent results.  

Speaking of which, hopefully some of you are following the T-Bone System again this season, and enjoying one of the longer winning streaks currently (see left). 

The 'official' ROI for straight up bets is 19.4% this season, and for Run Line bets it is 23.9% while to a level stake, the ROI is 20.9%.

There may be one more winner to add to that list, as the Athletics just qualified yesterday at -140 and beat the Tigers by 14 runs, but sometimes these borderline qualifiers drift and don't get counted officially. 14 runs would be the largest margin of victory for this system in over a year - when the Athletics were on the receiving end of a beating in Houston. 

Of course, this inefficiency should disappear, but these biases are persistent little devils, which is good news for those of us who enjoy making hay.

Hot favourites in baseball have performed well in recent seasons as readers will know, and after a losing March / April have resumed their winning ways this month.
Again, this isn't because favourites have a life of their own, and are pulling their socks up and trying harder this month. The success of this strategy is down to the public's resistance to betting on hot favourites in baseball, and the resulting inefficiency that is there to be taken advantage of.

The probability of these returns being by chance? Using a calculator I downloaded some time ago, I believe from Joseph Buchdahl's web site, I get the following.

Run Line:
Straight up:
Interesting how much difference there is between the straight up bets at short odds and higher stakes compared to the run line and its more even odds and stakes.

The numbers actually look too good to be true, and I should probably remove this post and all references to baseball betting, but even if they are correct, not everyone will be convinced by them, and that's a good thing. 

A one-in-a-million probability wouldn't sway some people. 

Matthew Trenhaile woke up after a long nap, more accurately after a long  hibernation, and has resumed activity on Twitter, which is good news. He is well worth following and recommended the BettingMarket web site.

Somewhat relevant to this post are these opening lines from an article there titled: On the psychology of the betting market:
Most punters lose. They are ill-informed, intrinsically lazy, psychologically flawed, impulsive, ill-disciplined, incapable of appreciating the importance of affect to the decision making process and prone to imitative and repetitive behaviour. When punters lose they typically come back for more (repetition compulsion); when they win, they become overconfident and prone to risk-seeking.
Long may this continue.  

Monday, 13 May 2019


While many of us are used to some rather strange, and often unpleasant, content from the Daily Mail, the below Tweet from their North-West football reporter Dominic King was a late contender for the "Most Ridiculous Tweet of the Season" award:

I personally don't see anything wrong with this practice at all. The league season is over, but even if it wasn't, I don't see why offering prices for next season, or any future seasons, should be considered 'shameless'.

Is there supposed to be an official mourning / celebration period at the end of each season during which respect is shown and the vulgar business of betting suspended? First I've heard of it.   

Possibly some projection at work here, as working for the Daily Mail would certainly fall into the 'shameless' category. 
Daily Mail, 15 January 1934

And if you want a more recent example of shameless from the Daily mail, here's a 'story' from today:

In the financial markets, prices are quoted for several years into the future 
Weather forecasts also make long range projections, and The Old Farmer's Almanac has done so since 1792. Shameless!

I'm not sure why football markets, or any markets for that matter, should be any different, and the use of the word 'shameless' in this context, is absolutely ridiculous. 

For those shameless enough to be looking to back Manchester City to win the league in 2019-20, Pinnacle have them priced at 1.714.  

Sunday, 12 May 2019

EPL 2018-19 Records

With 36 goals in the final round, the record for goals scored in the Premier league was broken with an average per game of 2.821, mostly due to the increase in Away goals which also hit a new high this season: 

Not surprisingly, Away wins ended the season above one in three for the first time in English top flight history: 
The Draw finished at a Premier League record low, the lowest percentage for Draws since 1931-32.
At the individual club level, no club had previously drawn fewer than three games in a Premier League season, but this season two teams (Manchester City and Tottenham Hotspur) managed that feat, with Tottenham just 15 minutes away from just one Draw all season. 

Two Draws in a season is a top tier record fewest for a 20 or more club season - Sunderland set the record in 1908-09, so for two clubs to match this in the same season (103 seasons in total) is quite remarkable. 

At the other end of the Draws table, only Southampton made double figures this season with 12, three clear of the next highest total. Like Tottenham, Southampton also drew their final game of the season. 

Twelve is the joint lowest 'winning' total in the Premier league era, matching Aston Villa's 12 in 2005-06, although in that season three other clubs also made double figures. 

This Premier League season is also only the second where the title would have gone elsewhere if we were still in the pre-1981 era of two points for a win. Manchester United would have won the 1994-95 title on goal difference from Blackburn Rovers, and Liverpool would be champions today. 

Look forward to more fascinating insights in the coming months. 

Tuesday, 7 May 2019

End of Season Goals

With just one round to go in the English Premier League, only a somewhat improbable clean sweep of ten draws next Sunday will prevent this season ending with the lowest Draw percentage in Premier League history.

It may come as a shock to some, but there was actually top level football prior to 1992 and here (left) is how the current season ranks overall for all seasons where fewer than one in five matches ended as a Draw.

Draws on the final day of the season don't occur any more or less frequently than in other rounds - some seasons zero (2017-18), others as many as six (2006-07), with an overall average of frequency of 21.67% since 2000-01. 

Backing the Draw in matches where the true difference between the teams is less than 25% and the ROI (using prices adjusted to an over-round of 102.5%) is 8.6% on the last day, not much different from the 9.13% over the 19 (almost) full seasons. 

No surprise that, once again, there are no Big 4 or Big 6 contests on the final day of the season. The last time this happened was in 2003 when Chelsea beat Liverpool 2-1 to clinch fourth place. It's almost as if this is by design. 

For those wondering about Aways, which is quite possibly no-one at all, the percentage currently stands at 33.24%. This season is already guaranteed to be the joint highest (tied with 2013-14) for Aways in top level English football ever, and just one more win will set a new high, with four more wins pushing the percentage above 33.33%. 
The total number of goals will also be interesting to watch. 31 more, and we will have an all-time Premier League record, while a low scoring final day with less than 16 goals (highly unlikely) will see the season finish eighth all-time. 

The final day sees an average goals per game of 3.12, with a high of 37 and a low of 23, so a new record is well within reach.

Saturday, 4 May 2019

Treasure For Sale

The infamous Gadoon Kyrallos, aka Spanky tweeted:

I have a copy of that book, and actually re-read it after reading Spanky's recommendation thinking I may have overlooked something, but aside from some interesting background as to how money line and point-spread betting came about, and the role of a bookmaker, and the importance of finding the best prices (soft lines), but surely anyone who is reading this knows about the principle of only betting when you have value. There's little else of any value in it as you might expect from a book written before the Internet was in common use. I replied to the tweet:
I re-read this book a few weeks ago. It’s outdated and not worth 80 cents, never mind $800. Got some interesting historical references admittedly but won’t give you an edge in today’s markets.
Spanky's response: 
My success in sports betting is based on the underlying principles in that book. To each his own brother. One mans junk is another mans treasure.
The conversation continued:
Seriously, if anyone wants to offer me $750 for the book, it is yours, and I'll even pay the postage and insurance.

** Update 5th May 7am: I don't make a habit of editing posts, but I just now came across a 2007 review of the book in question on the Las Vegas Revealed web site, and thought I would post it in full:

Reviewed by Nick Christenson
July 18, 2007

I only rarely write reviews of out-of-print books, and then usually only for those books that have some sort of timeless significance, such as Mike Lee's Betting the Bases, or David Hayano's Poker Faces. Certainly, I can't say that Jack Moore's, The Complete Book of Sports Betting belongs in this elite company. In fact, I debated with myself as to whether I should write this review at all. I do think that Moore's book is interesting, though, and it deserves more attention than it has gotten. The reader will ultimately need to judge whether it is worth seeking out or not.

Moore offers a new, at least new at the time of its publication, strategy for winning at sports betting. As such, the principle target of the book are those who have tried other methods of winning at sports betting, and presumably failed. It is these folks who are in a position to appreciate the novelty of Moore's approach. The author does not take for granted prior knowledge of sports betting and its terminology, though. He provides a great deal of background aimed at equipping the novice with enough information to understand the the complex jargon of the bookmaker. Even just a decade after publication, some of the methods for quoting odds that Moore describes are no longer in common use, but the introductory material is good and devoid of the silliness that pervades many other books on sports betting.

About 60% of the way into the book, we finally learn Moore's secret to winning at sports betting. This method is simple enough to be described here, and since the book is now out of print, I don't feel bad about revealing its secret. The method Moore espouses is to assume that the consensus betting line is an accurate measure of the proper game line. Then look for shops with betting lines that differ significantly from that consensus, and then bet them. With this method there is no handicapping, and Moore calls it the "blindfold method". The author is not the only person who espouses this method as a component of a winning sports betting strategy. The well-known sports bettor who goes by the name of "Fezzik" uses a similar method as the cornerstone of the way he bets.

While I believe that Moore's strategy is fundamentally sound, I'm not as impressed with some of the details he provides. He states his opinion on how many points of deviation from the consensus line one needs in order to make bets of a given size, but these seem to be based on the author's intuition and experience rather than a careful examination of years of data from each sport. Also, in some sports, especially American football, not all points are created equal. Moore explains the value of the "3" and "7" in the NFL and college football earlier in his book, but in his betting method a line move between 2.5 and 3.5 should be considered the same as a line move between 4.5 and 5.5. Anyone who has studied football results will understand that this is absurd.

Consequently, I would say that Moore's "blindfold method" represents a reasonable beginning for a strategy that can be used to win at sports betting, but is incomplete as it stands. Some more number crunching, especially for sports such as football, will be necessary in order to turn this into a reliable winning method. Also, the author's recommendation that having three different "outs" at which one may bet is probably not sufficient to generate much betting volume. This is due to the efficiency with which information propagates these days, largely due to the Internet. On the other hand, the Internet makes it much easier to obtain access to multiple lines and efficiently compare them. The upshot of this is that one probably wants many more than three outs to successfully apply this method.

Moore's book is interesting, and if it were still in print (and accounted for the emergence of the information age), I would be happy to recommend it to those interested in sports betting. Because its methods aren't "sexy" and don't allow bettors to put money on their favorite teams more often than others, Moore may not have ever gained a large following. However, since his book is devoid of the sort of misinformation that fills so many other volumes, he deserves significant credit for accomplishing at least that much. I don't think it rises to the level of "must read", and in my opinion those who have made it this far into this review now know over half of what the book has to offer. Still, the book deserves some consideration by those who are interested in the subject of sports betting.


In the out of print book, The Complete Book of Sports Betting, Moore advocates a market-based approach to winning at sports betting. I believe the basis for his method is sound, although I don't believe the book contains everything the bettor needs in order to succeed with it. I wouldn't rate this book as a "must read", but since it is significantly better that the average book of this genre, and because it approaches sports betting from a novel vantage point, I certainly wouldn't discourage those interested in sports betting from seeking out a copy.

Again, if you would like my copy, please send offers, while bearing in mind the ebay price is currently just under $500. 

Friday, 3 May 2019

Draw Collusion

When a draw suits both teams in Italy, the game will end in a draw. It's all to do with the mentality of the Italian people. They see nothing wrong in such an arrangement. - Liam Brady
I have written several times before on the Draw in Serie B, and it is that time of year again with Future Greyhound calling me to task for my observation that the Draw can never be the Favourite in a football match: 
Enjoy your stuff Cassini. But as a pedant I must point out the Draw definitely can be Fav in football. Draw Collusion has been a studied topic (USA v Germany 14 WC & Uruguay v Mexico 10 WC) and think Draw was Fav in one of those from memory. Don’t get me started on Seria B!
Nothing wrong with being a pedant, and of course, the Draw can, and sometimes is, the market favourite, but my statement was intended to refer to matches expected to be played competitively.

Future Greyhound mentions Serie B (actually he references Seria B, but only a pedant would point out the mistake) and since Pinnacle's Closing Prices were added, i.e. the 2012-13 season, the Draw has been the favourite in 37 matches, including six this season already. 

Incidentally there were no prices available on another 25 matches, all of which were May games, 10 of which resulted in Home wins, while the other 15 were all Draws. Possibly other bookmakers were offering prices on these games, but I doubt that you would have been able to bet too much on them.

For those 37 matches where we have Pinnacle's prices, backing the Draw would have been profitable to the tune of 23.4%

In 489 other matches where the Draw was priced at 3.0 or shorter, backing the Draw would have lost you money, something that is not easy to do in this league.

Blindly backing the Draw in the Pinnacle era, and you'd be up 160.35 points from 3,070 matches, a decent ROI of 5.22%. My strategy of calculating the 'true' difference between the teams increases this to 7.59% across almost seven seasons.

Tuesday, 23 April 2019

103%, NHL and NBA Playoffs

Another couple of Draws in the last two nights, including one (Chelsea v Burnley) rather unlikely one priced at 6.46, the second highest priced draw of the season. 

It was the 46th time this season that the (Pinnacle Closing Odds) overround has exceeded 103%, which doesn't compare favourably with just 8 matches in the whole of last season, and none whatsoever in the three seasons 2014-17.

After last night's result, it's now actually a profitable strategy to back the Draw when the overround is above 103%, but I wouldn't recommend it. This season overall is tough enough for Draw backers as it is:

but since 2000-01, it's consistently a poor proposition:
The Stanley Cup playoffs are now in full flow, and after a slow start, the COAL system I follow is finally in profit after three wins in the last four games:
As is almost always the case, the 'official' price for tonight can be improved, with 2.32 currently available on Betfair and to add to the excitement, it's a Game 7. 

In the NBA playoffs, after a promising start, recent results haven't gone in our favour:
No selections today. 


Monday, 22 April 2019

Pinnacle 3 Football Data 2

For the first time since Groundhog Day, there were two Draws in the English Premier League on the same day this weekend, so the Draws percentage increases slightly to 17.44%, still a clear low for the EPL. 

Four Away wins increases the percentage of Away wins to 33.72%, a clear high for the top tier in England all-time. 

It's not a coincidence that the average goals per game this season is currently 2.826 (more goals means fewer Draws), which is an EPL era high, while the average number of Away goals per game (1.244) is also at an EPL era high.

There's been some discussion on Twitter about the increase in Pinnacle's over-round this season, noticeably in games where there is a short priced favourite.
One suggestion was that it might be due to Football Data only giving prices to two decimal places, even when odds-on. 

I do agree that Football Data should use three decimal places to keep in sync with Pinnacle, but I don't agree this explains the observations this season because Football Data has always used two decimal places (occasionally three) and the big increase has only been seen this season. 

As mentioned, Pinnacle themselves go to three decimal places quite often, as can be seen from the current EPL prices:
The Chelsea v Burnley game tonight currently has an over-round of 102.984%. 

If Football Data round this to 1.26, the over-round drops slightly to 102.921%, but if, heaven forbid, the price is being truncated to 1.25, that makes a big difference with the over-round soaring to 103.556%.

Even with rounding in play, which I presume is the case, that extra digit can make a big difference, with a price of 1.255 being recorded as 1.26, the same as 1.264. Using the Chelsea game above as an imperfect example, but for the sake of argument, a 1.255 price would give an over-round of 103.237% while a 1.264 price gives a value of 102.67%. (In practice, the Draw and Away prices would move, but this example illustrates the difference rounding can make).

Looking at matches where the home team is priced at 1.3 or shorter, the average over-round between 2012-13 and 2017-18 ranged from a low of 102.04% in 2016-17 to 102.21% in 2017-18, before this season's jump to a current 103.08%. 

Friday, 19 April 2019

Shorter Odds, Greater Margin

Last night's Los Angles Clippers v Golden State Warriors official total of 236.5 points was the highest in database history, which goes back to the 2002-03 season, but Overs came in at 237.

The previous high (234 points) was Tuesday night's Game 2 between the same two teams in Oakland, which went Over by just 32 points!  

As you can see from the screenshot, I was on last night at 235.5 points, for a relatively comfortable win at 2.08.

Incidentally, I really don't like the way Betfair do their total and handicap markets these days - they are certainly almost impossible to trade in-play, and even getting on pregame is confusing. 

There was some discussion on Twitter recently regarding Pinnacle's margin increasing in the larger football markets, the top divisions in France, Germany, Italy, Spain plus the top two in England.

@entwolken produced a chart showing the margin increasing from 2% between 2014-17, to 2.2% / 2.4% over the past two seasons. 

Pinnacle emerged in 2012, and based on closing odds the over-round from 2012-17 was 102.08%, in 2017-18 was 102.11% and in 2018-19 is currently 102.33%. 

For the most part, the higher margins are seen on matches with a hot favourite, something I pointed out several months ago

Of the highest 52 margins (left) in the last five seasons, only two had a favourite priced over 1.4.

44 of them are from this season, 8 from 2017-18, and none from 2014-17.

With more 1.2 or shorter favourites in the past two seasons, than in the previous five combined, it's not hugely surprising to see the average margin increase, but if you stay away from matches with short favourites, the over-round is still only 102.1%. 

I say 'only' because we are now spoiled. Back in 2000-01, the figure was 112.54%!   

And for those of you wondering about the outcome of backing all those 1.2 and shorter favourites, you'd be up 3.62 points, an ROI of 3.73%. 

Back in the Spring of '69

A rare personal post today, since it is 50 years to the day since Crystal Palace clinched promotion to the top division, then called Division One, for the first time in the club's history.

A very young Cassini had seen his first Palace game almost exactly two years prior on April 22nd, 1967 and a very old Cassini can still recall the excitement of that 1968-69 season. 

Palace lost just one league game after 7th December, and I can still remember the win at runaway leaders Derby County (managed by Brian Clough) in early March as the moment it seemed genuinely possible the dream might come true.

For perspective, prior to the 1961-62 season, Crystal Palace had played all but four seasons (1921-25) of their league history in the lowest division, either Division 3 South or Division Four, since entering the league and winning Division Three at the first time of asking.

The 1950s had been disappointing to say the least, with Palace having to apply for re-election three times (a record for a current Premier League club, although one that Norwich City with four might take over next season), and were knocked out of the F A Cup by a non-league side three seasons in a row during that decade:
Promotions in 1961 and 1964 were followed by the 1969 promotion season, one disrupted by postponements including two versus Oxford United. 

Palace played only seven league games in three months, December through February, which meant a busy March (8 matches), and three games in four days over Easter, a crucial 11am game at home v Middlesbrough who were level on points with Palace at the time, followed a day later by a home game v Portsmouth, easily despatched (as usual) 3-1, and a game the following Tuesday at Huddersfield Town.

Promotion was finally clinched on 19th April after Palace came from 0-2 down to beat Fulham 3-2 on a sunny afternoon in front of 36,126 fans. Club legend Steve Kember scored the winner, and it wasn't the last occasion that he would feature in end of season drama, and always on the good side of it!  
Fascinating to read in the programme for a Friendly match in May versus Morton, how low key the comments of manager Bert Head were:
"Tonight's game gives all our spectators an opportunity of sitting back and enjoying a match without the tremendous tension associated with our last battle against Fulham. I sincerely hope everyone enjoys the game and - like me - is looking forward to the coming season."
They did things a little differently back then. I'm a Palace fan because my Mum lived in the area when I was born, and thus they were my local team, and first team I ever saw live. They have been a constant in my life for almost 52 years, and although they may not win too much, life is seldom boring. 

On the 23rd April that year, Palace did win the London 5-a-Side Championships at Wembley. 
Oh, when I look back now
That summer seemed to last forever
And if I had the choice
Yeah, I'd always wanna be there

Those were the best days of my life

Back in the summer of '69...

Sunday, 14 April 2019

La Liga, X-Weighted

Yet another English Premier League day with no Draws, and the percentage falls still further to 17.37%, the lowest in 114 years. Manchester City's win at Crystal Palace took Aways to within a whisker of 33.33%, with 111 wins in 334 games. 

@FootyInvestor mentioned the contrasting abundance of Draws in La Liga this season and at 29.97% at the time of writing, the current strike rate is beating the 29.47% of 1999-2000. 

From a betting perspective, the strike rate is, of course, meaningless. The strike rate could be 50%, but that doesn't mean backing all Draws would necessarily be profitable, since it all depends on the price. Finding matches where the Draw is under-priced is the key.

Regarding La Liga, I wrote last Summer that: 

Using the relative difference in win probability between the two teams works well in this league, with the Draw in matches up to the 25% level generating an ROI of 8.81%.
As I did last year, I am planning to take a look at some of the leagues again, but as a sneak preview, I can say that if you followed the advice above, you'll be aware that the trend continues, at least so far this season, with an overall ROI of 23%. If you weight your bets, increasing stakes to account for the narrowness in difference the difference, ROI increases to 36.85%. While level stakes are the only way to measure the strength of a system, the optimal staking method is to adjust stakes depending on the perceived edge, i.e. Kelly.

Here are the results so far this season on the La Liga matches expected to be the closest:
One season is far too few matches to 'draw' any conclusions from, but going back to 2012-13, this method has an ROI of 23.6% to level stakes from 149 matches. 

Interesting to note the range of prices on these games, from a low of 2.98 to a high of 3.62.

Our sceptical friends, awaiting statistical proof, won't be convinced that there are opportunities here, but for mere mortals of us living in the real world, such consistent returns are, in my opinion, worthy of interest and indicate an area of inefficiency in the market. 

Waiting for statistical proof is great if you are trialing a new drug, but in ever changing betting markets, it's practically useless, by which I mean it is useless in practice.    

Saturday, 13 April 2019

The EPL Draw Picture

It's becoming a familiar story - another weekend, at least so far, with no Draws in the English Premier League, and the dry run since March 16th continues. 

The 2018-19 season has now seen the lowest percentage of drawn matches since 1904-05, with 1931-32's 17.75% record now passed.   

If none of the three remaining games tomorrow and Monday night finish all-square, the 1889-90 percentage will also be surpassed, although 'surpassed' seems an inappropriate choice of word to describe this potentially momentous event.

Away wins this season are still atop the 120 all-time seasons table at 33.13%, courtesy of Newcastle United's win at Leicester City last night and AFC Bournemouth's demolition job against Brighton and Hove Albion earlier today.

It's all very fascinating, but a curiosity rather than a money making opportunity. Fortunately with the playoffs now underway in both the NBA and the NHL, and baseball in full swing, we have plenty of those.

Yesterday's NHL qualifier lost, but we have one selection today and one tomorrow. 
To clarify the years and seasons, I have updated the table which now looks like this:
No qualifiers for the NBA playoffs today, and none for the Basic T-Bone System, which is picking up after a slow start: 

The Importance of Assuming Positive Intent

The NBA Playoffs start this evening, and there are some strong trends on the Totals in the first round that I'll again be following this season.

The numbers won't convince TechnoRondo, but I like them, going back eight seasons to the 2010-11 season, and profitable in every season since 2011-12. 

I was thinking of tweeting the details for your consideration, but have had the misfortune to run into two rather dim and rude characters on that platform this morning, who seemed to have got far too confused by this screenshot from last night, and it's rather dissuaded me from wanting to share anything at all.  
As readers will know, the "Season" in my blog always refers to the year the season started, which is not a problem for MLB or WNBA, but can be confusing I guess, for sports that start in one year and conclude the next. So in the context of NHL playoffs, Season 2018 refers to this current season, as I also made clear in my blog:
It's really not rocket surgery, and if someone struggles with this, then they may well not be cut out for sports investing, clearly lacking the analytical skills required, but we go from my polite explanation to this accusation:
Two errors? I can't recall the last time I made ONE error, never mind two!

If / when I get a polite answer to 2 and 3, I might give the two teams and explain his error in logic, but I really don't understand the need to be rude just because you don't understand something. Based on this encounter, I'm thinking he must be rude all the time!

"Assume positive intent" is a good rule to live by. Don't accuse someone of falsifying data just because you can't work out the answer. 

Friday, 12 April 2019

COAL Face-Off

A lot of analysis is garbage, but there are inefficiencies in the market that make 'coming off a loss' a strong trend to follow in the Stanley Cup playoffs.

Here are the results of one COAL playoffs strategy by season, since as far back as I have access to the data, including the first two selections this year. 

It won't convince TechnoRondo, but it's good enough for me to risk a few pennies. 
We're on the Pittsburgh Penguins tonight, as we were on Wednesday although an overtime lost cost us the win on that occasion.

Models, Balancing and Unconvinced at 18-0

My last post attracted some interest, with a record number of comments and 'likes' on Twitter. The days of people commenting on blogs seem to have passed, but on Twitter they are alive and well. I don't always tweet my new posts, some are admittedly not hugely interesting and seem unworthy of a tweet, but for the ones that are touching on areas of high interest and controversy, I should probably do this as a matter of routine to keep the conversation going. Some highlights are reproduced below.

l0l0 started the ball rolling with some thoughts on the bookmaker's process:

the process I imagine:
1)calculating "true" probabilities
2)knowing the habits of your clients, distort the offer in order to have an equilibrate state of the book at the end to match the "true" probs

3)make noise(publish 'betshares') when the book isn't close to equilibrium
I think this is about spot on. I would add that they should be managing limits so that the earlier lines are open to smaller bets than the later lines as the consensus on the price builds, We actually see this on major sporting events with Pinnacle when they announce closer to the start time that limits are now at some huge number. Regarding the 'habits of their clients', if they have a client who for example bets only on Maidstone United matches, and has a high success rate, they might well be happy to have all their green on this outcome and risk a zero profit or even a small list on the other outcomes but a well run business can't afford to take big risks.

On this topic, Joseph suggests that:
@aluckyaday is probably right. Some of it will be weight of money, some of it will be bookmakers exploiting squares, and some of it will be bookmakers attracting new customers. The picture is nuanced.
We are in agreement. Doctor C ( @oddsvantage) writes, in language highly unsuitable for a family blog, but I'll let it go this one time:
So does this mean that people have such a hard-on for Pinnacle prices because they don't block/limit sharp punters (which allows for improvement on their odds) rather than because of their analytics and models?
Regarding the idea of 'loss leading' prices, Joseph clarifies that he is referring to recreational bookmakers. I really don't give these organisations much thought, because in my opinion and experience, betting with them is unsustainable if you are even slightly sharp. But sure, if you are clueless or a novice, you can get some generous prices. Just don't give up your day job for them:
My WOCs system cannot possibly work because squares are this dumb to force bookmakers to offer thousands of loss leading prices. Recreational bookmakers do this to attract new customers by selling the "we offer great prices" message. Then they ban for regular exploitation.
Indeed they do.  

Ian ( @maxpowers1981 ) and Joseph get into something of a spat, with the conversation started off by Ian suggesting that:
Balancing books is a load of nonsense. It's a sub optimal strategy. Doesn't exist in practice generally.
I'm not sure what evidence Ian has for this assertion, none was offered, but the idea that that balancing books is a load of nonsense seems to be itself a load of nonsense. No one is suggesting books are almost evenly balanced across all outcomes, but a book that starts gambling isn't going to be in business long, and there are certainly several books that have gone out of business in the past. A well run business like Pinnacle don't need to take risks. 

Anyway, the man from Del Monte, Jez, chimes in with a pithy comment:
You may be the only person in this thread up to now who actually has a bet, Ian.
An unsubtle dig at Joseph perhaps, who admits to not being a gambler, and who rises to the bait, responding:
You may be the only person in this thread up to now who has contributed nothing, Jez. My threads are to facilitate debate about things which are to a significant extent unknown and uncertain. I don't see your name in the Forbes rich list, so presumably you're not sure either.
Ouch. Jez:
Two tribes. Those who gamble - however moderately - and those who just like collecting numbers as a hobby and would otherwise be on a draughty platform at Crewe taking them off trains.
There are certainly some people on the thread who are known not to bet but who have no job and spend several hours a day tweeting profusely and writing absolute nonsense, but we're not here to name names. I've written in the past that for me, sports investing is my video game replacement:
I was thinking in the shower this morning, (yes, once a week, whether I need one or not), Betfair really is the ultimate video game. I've never been one for games, (friends at work spend hours playing Call of Duty - why? What's the point?), but in many ways the exchanges are one big on-line game. It's me versus an unknown opponent. My opinion versus yours, except in this game the points are real money.
The 'real money' part is important since it is absolutely pointless to study markets and look for edges if you're not going to make money. 

Regarding my clarification of the ROI and P-values calculated by Joseph:
I'm not sure Joseph has got his ROI calculation quite right, because an ROI** of 104.8% from 3,511 bets would certainly be impressive. I think from looking at his chart, theoretical profits are actually 168.53 points, which is a far more modest, but still decent, ROI of 4.8% and a P-value of 2.341 assuming average odds of 3.0, a far cry from the 0.0006 tweeted. Or am I missing something here?
Joseph replied:
Yes, you were missing something. I used my yield distribution calculator rather than my p-value calculator. The later is programmed to compare ROI to break even (ROI - 100%). In the former, I set it to the blind betting returns which from memory was around 97.5%
I'm still not clear on what the P-value should be or what I am missing. Is the ROI 104.8% or 4.8%? Is the P-value 0.0006 or 2.341? 

Anyway, @TechnoRondo commented:
Good article with some fair points. However, stuff like "this pattern was there in 17 of 18 of the seasons that pattern in 12 of 13 last seasons" etc is imo not really convincing.
The word 'pattern' was not used by me in those examples. I see a big difference between identifying an area of the market that is perennially inefficient, versus something that is a 'pattern'. 

A 'pattern' to me would be something like that in every third year, favourites priced between 1.63 and 1.87 are profitable in the AFC when the game is played during the day in a domed stadium, i.e. completely random and useless.

When 18 of 18 years sees a 50/50 chance tilt one way, (one year there was a small loss due to commission, even though there were more winners than losers) I'm happy to accept that the market isn't efficient. This is more than a 'pattern' because it's not random; the a priori is that bettors have a tendency to favour home favourites. We have a hypothesis, and the data appears to support that. Maybe not statistically proving it, but as I wrote in my last post, you can't wait that long and markets correct themselves. Usually. 

Do I think this market will continue to be inefficient? No, but I said that ten years ago when it was 8-0! 

At what point would TechnoRondo be convinced? 35 out of 35? 

I'd suggest that if you're unconvinced with a record of 18-0, then you'll never be convinced, and you really might as well be standing on a draughty platform at Crewe spotting trains.

I mean seriously, what record would be convincing? 

TechnoRondo continued with:
First you should get a limited set of patterns (draws between equal teams could be one). After this it should hold in several competitions / seasons (large samples are necessary). Otherwise it is still gambling but no longer on football games but on bookmaker patterns.
Again, these are not 'bookmaker patterns'. Prices are "in general" determined by the money coming into the market. As for looking at several seasons and different leagues, I looked at several leagues and divisions in June 2018. for example from the Championship review:
For games where the difference is 25% or less, the profit is 23.14 points, ROI 2.3%, which is a lot lower than the same parameter produces in the Premier League.
I may do the same again this summer if time permits, but I wouldn't expect the same results from lower leagues as from the EPL as the markets are different, both in terms of volume and the participants. 

A Priori, Patterns and Sceptics

Not for the first time, and probably not the last time either, Joseph Buchdahl generated some responses and interest with this Tweet yesterday:

I'm not sure Joseph has got his ROI calculation quite right, because an ROI** of 104.8% from 3,511 bets would certainly be impressive. I think from looking at his chart, theoretical profits are actually 168.53 points, which is a far more modest, but still decent, ROI of 4.8% and a P-value of 2.341 assuming average odds of 3.0, a far cry from the 0.0006 tweeted. Or am I missing something here? 

Joseph shares another profitable "system" although again hugely inflates the actual ROI% and P-value, and then a losing "system" although most readers would be very happy with an ROI of 92.8%! 

His conclusion was: 
don't be a schmuck and believe everything you see has a reason for being so.

Learn what regression to the mean is and don't be fooled by randomness.
Joseph later retweeted his initial Tweet and directed it to someone called Massimiliano “Maxi” Imparato with the message:
It appears that this Massimiliano, who started looking at Draws late last year, is now selling something called the "Golden6 system: new betting strategies to take advantage of draws" using slogans such as:
The best time to bet on draws was 7 years ago. The second best time is now.
While I agree with some of his spiel, his overviews of his six systems are heard to understand, and some appear to be complete nonsense, with the word 'pattern' appearing several times.
Golden6.4 Missing Draws: The home team comes from a small streak without drawing, and a game of uncertain outcome is played. This run without draws can cause value in their odds.
Aren't ALL games of "uncertain outcome"? And what does a 'small streak without drawing' mean? Basically nothing, except that a pattern has been found that has no predictive value at all. I guess a small fortune was lost this year on Tottenham Hotspur, chasing that overdue Draw!

However, I do know that backing the Draw in certain types of matches, has been, and continues to be, profitable. For the English Premier League, the hugely successful XX Draws service had these results in its three short years of existence: 

Presumably Maxi is offering a money-back guarantee for any seasonal losses, a step first taken by this ground-breaking service, even if it was never needed?

As I have written before, the idea of the Draw sometimes being value was first suggested, at least to me, by Derek McGovern in his 1999 book "On Sports Betting...And How To Make It Pay". Page 87. 

His ideas were reinforced ten years later by an article by Kevin Pullein, a name many readers are probably familiar with. Pullein stated that one of the major factors influencing the result of a football match is "the difference in ability between the two teams". Not rocket science, but the article went on to explain why the draw can be value in certain matches.

The work of David Sumpter more recently has confirmed the idea that in some matches, the Draw offers value. Sumpter has written about this using the Big 6 for his system, although Joseph dismisses the results writing:
I don't believe his [Sumpter's] "inefficiency" is real. The sample size is too small. I've given you samples in the thousands with big profits to closing Pinny prices, never mind junk bookies, that are totally worthless.
I don't like using all the Big 6 matches myself, as teams have off seasons when they are not so Big, and it's more important to select matches where the win probabilities are close, whether they be Big teams or not.

And agreed, it is a small sample, since we only have Pinnacle's closing data going back to the 2012-13 season, but we have prices from other books going back to the 2000-01 season - all thanks to Joseph I might add.  

These pre-Pinnacle seasons had over-rounds in excess of 112%, but if we adjust the odds to reflect an over-round of today's 102% for the nearly 19 seasons in the EPL, looking at Big 6 (or earlier Big 4) matches where the two teams had win probabilities within 10% of each other, the ROI is 29.14%

Yes, it's a small sample, but it's all we have. There is only one Big 6 and one EPL so we have to make the best of it.

Despite the roots of the 'Draw can be value' idea going back twenty years, and presumably satisfying Joseph's requirement for some logic behind the idea:
...but you would be a fool to look for anything and believing there was any point to it unless you had previously developed a methodology that could explain why this pattern occurred.. That is the point of this thread.
To my way of thinking, it's not a pattern, and it's not random, if you call it out ahead of time. 

Joseph remains unconvinced, because he is looking for statistical proof:
No one has convinced me that draws systems don't simply mean regress because they are based on nothing. 
They're not based on 'nothing' if they are based on ideas first aired in public twenty years ago, and as I have previously written, "betting markets are not ideally suited to the traditional standards of proof, mainly because they are constantly evolving and adapting and if any edge is present, it should soon be discovered and the market will adapt accordingly."

If we forget the Big 6, and use all the data we have from those (almost) 19 seasons, and just look at matches where the two teams had win probabilities within 10% of each other, the results are still good, with an ROI of 7.79% from over 500 matches. At 20%, the ROI is 9.65%, from 1,107 bets. 

It's interesting to look at the Draw price in those 1,107 'close' games. You might expect it to be generally around 3.4, which is indeed the average, but the price ranges from 2.88 to 4.08. If you back only in matches where the Draw is priced at the higher end of scale, profits are greater. E.g. at 3.6 and above, the ROI is 30.9%.

I guess the choice is that of the individual - wait until we have statistical proof of a system, (with 30 Big 6 matches a season, I'll be 137 by the time we have a big enough sample), by which time paradoxically, the secret is out and the edge has long gone, or we make hay while the sun shines, and if the system stops being profitable, look elsewhere. You're certainly not going to make any money waiting for solid proof from the sidelines.

Edges should not last for long, but they do tend to persist far longer than it would seem reasonable to expect and that is because betting markets are not made up of rational people. 

Does it make sense that backing small underdogs on the road (College Football) would be profitable 17 of the last 18 seasons? That small road 'dogs in the NFL are profitable 11 of the last 13 seasons? That NBA road favourites after a loss are profitable 11 of the last 13 seasons? 

I could go on, but there's a difference between identifying inefficient markets (because the public likes favourites, or doesn't like favourites if they lost their previous game) and finding random patterns in past data as Maxi seems to have done, at least in some systems. Apparently he has something like 150 which is a sure sign that he's a little confused and selling trash based on patterns and data mining. When Golden6.147 starts to show a loss, it'll quietly be dropped while the virtues of Platinum12.833 are extolled. 

Doctor C tweeted:
I think the example [from Joseph] is to highlight the pitfalls of blindly believing some of the false patterns that can be found when data mining and the importance of splitting data into training and validation sets. I think....
Joseph wrote:
IMO the only way to profit from draws is to back draw prices that are deliberately offered as loss leaders.
That would only make sense if a bookmaker were saying "you can have 3.8 on the Draw if you also bet on a horse in the 3:30 at Chepstow". I don't think it works that way. Why would a sportsbook offer a "loss leader"?

A Draw, like any other outcome, is offered at a price because the book wants to attract money on that outcome, and balance their ledger. If money continues to pour in on the Home and Away, the draw should lengthen. 

Messrs. McGovern, Pullein and Sumpter have all explained why the Draw price is sometimes higher than it should be, and my experience with the Draw tells me they are on to something. Anecdotally, how many times has someone, a neutral, watching a game on TV, told you they put a fiver on the Draw? 

A Lucky A Day tweeted:
I wouldn't read into this that they risk a loss in just about every market. I would interpret this as meaning that their books are seldom evenly balanced, so that one outcome will always be more favourable than another to them. I'm sure on occasion they may even take a loss, and perhaps are happy with a push on one result but a bigger win on others, but if they are intentionally taking risks on markets, then they are not the well run business that they appear to be, and we probably should withdraw our money now. There's also likely a PR element to that statement from their traders. A "we're all in this together" kind of thing.

If Pinnacle's lines and prices never moved, then I could accept the statement above, but the fact is that they do move, often significantly, and the reason is simple. They want to attract bettors to one outcome and deter them from another, and they are not shy about tweeting out meaningless 'betshare' numbers to help accomplish this.

For the record:    

** The return on investment formula is:
ROI = (Net Profit / Cost of Investment) x 100