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Saturday, March 6, 2010

Olympics, Scotties…and Brier Preview

We’ve been overloaded with curling these past weeks with the Scotties, Provincial Mens, and the Olympics all taking place since my last major article. I’m going to attempt some analysis of various situations that have taken place over these many games, and try to provide some preview for this weeks Tim Horton’s Brier in Halifax where yours truly will be sitting in for Luke Coley in the CurlTV broadcast booth. Luke had commitments with both the Olympics and now the Paralympic Games, and someone at CurlTV was crazy enough to give me the online microphone for the entire Brier. My apologies in advance.

Now on to the article:


Tie-breaker: Krista McCarville (Ontario) vs Jill Thurston (Manitoba)
The score is 0-0 in the 2nd End, last rock of the end belongs to Ontario. Krista faces the following with her last shot:

The immediate question the team debates is whether to draw for a single or play the run back for 2 or possibly 3. What’s the math on her decision? With 8 ends remaining, winning probabilities are as follows:

1 down with hammer, WP = .44
1 up without hammer, WP = .56
2 up without hammer, WP = .7
3 up without hammer, WP = .84

When they make the run-back, let’s assume they are able to score a deuce ¾ of the time and score 3 the remaining 25%. Let’s also assume if Krista attempts to draw for one she misses 10% of the time.

.44(.1)+.56(.9) = x(.7(.75) + .84(.25)) + (1-x)(.44)

Solving for x = 36.5%
Krista needs to be confident she will make a multiple score well over 1/3 of the time for this to be the correct call.

A simple way to estimate this on the ice might be as follows:
If I draw I’m between 44 and 55%, say 52%.
When I make the run-back, I usually score 2 with is 70% but sometimes score 3 which is 84%, lets, say 74%. If I make a run back 1/3 the time then my winning percentage is approx. 30% + 25% = 55%.

It's not exact but does provide simple way to make these decisions in real time during a game, even the skip isn't a math professor or poker player. 

Ultimately, they decide on the run back and Krista executes a spectacular shot, scoring 3 and cruises ahead to victory.

Alberta Mens Provincial Final: Kevin Koe vs. Randy Ferbey
Team Ferbey loses their third Provincial final in a row.  Close early, but steals in the 5th and 6th ends put Koe up by three. In the 7th end, Randy chose to draw for a single rather than blank. Winning probability with 3 ends remaining is as follows:

3 down with hammer, WP = .07
2 down without hammer, WP = .06

Numbers indicate this is not a bad decision, either scenario is close.


1. Sweden (Niklas Edin) vs. Great Britain (David Murdoch)

Sweden is up two in the 9th end and Murdoch has the hammer, In an attempt to blank the end, he hits and sticks for a single. Announcers Russ Howard and Cathy Gauthier both state the blank is preferred, however, if you’ve read the “Extra-End” portion from my article from here: may recall that Kevin Martin intentionally took one in the same scenario against Kevin Koe in the 2007 Alberta Provincial Final. That article is several years old and more recent statistics still hold true.

Winning probability with one end remaining:
Two down with hammer, WP = .117
One down without hammer, WP = .107

I only hope the scorekeeper didn’t deduct too many points from Murdoch’s “miss” on his blank attempt. This is another example of how shooting percentages never tell the whole story.

2. The Final: Canada (Cheryl Bernard) vs. Sweden (Annette Norberg)
Firstly, a fantastic showing by Team Bernard all week. They represented Canada well and played their hearts out. It was afinal game that could have gone to either team. The focus in days since has been discussion on missed shots, but it should be remembered for some of the great shots made throughout the game as well as the entire week. For example, in the 2nd end, Bernard makes a nice corner freeze on her first when Sweden had them under pressure. In the 5th, Cheryl makes a great shot to freeze on top of the Sweden stone and nearly gets shot. Norberg then makes a great draw to the button for two. In the 6th, Cheryl makes a great draw on her first, Norberg then makes a spectacular run back and sits shot buried on top of the button. Cheryl then calmly makes the soft hit for a single. In the 7th, Cheryl makes a great shot to sit two behind the centre guard and, after Norberg misses, is able to steal a huge two points and make the game close.

4th end Bernard chooses to hit the Sweden rock in the four foot and play her corner guard on leads second rock, allowing the opponent to attempt a peel with second’s first rock. The peel is missed (nose hit). I don’t mind the strategy during the early game, encouraging Sweden to not play a centre guard. This is a strategy that would be very questionable in the Mens game but has some validity in the Womens where the chance of a missed peel is higher.

7th End. On Norberg’s last rock, she chose to draw tap Bernard’s shot rock sitting half open in the back button.

She alternately could have chosen to blast it out and give Canada a single, retaining hammer in the 8th and be tied. If she is too tight they likely push the Canada stone top four out instead, though perhaps some small chance it jams on the Swedish stone at the side of the rings. The winning probabilities for Team Sweden with 3 ends remaining are as follows:

Up 2 without hammer, WP = 79%
Tied with hammer, WP = 61%
Down one without hammer, WP = 40%

I like the call, but she made a bad miss by not at least having tee-line weight to at least cut down Canada to a single.

8th End. Bernard calls for a peel on the Swedish corner guard with second’s final stone. This appears to be a conservative call and she could have opted instead to maintain the pressure by playing a tight centre guard or drawing around the Canada stones staggered at the top of the house. They now bring a possible blank into play. I really like this play but uncertain if Cheryl understood the mathematical reasons. Statistics for Womens has an interesting situation at this stage:

It is more advantageous to be one up without hammer than tied with hammer when two ends remain. Cheryl’s WP = 61.5% tied with hammer and 62.5% if one up without hammer, starting the 9th end. This situation does not occur in the Mens game. Some of you might suggest these numbers are very close and 1% is not a significant advantage. That is partially true, but what it does indicate is Canada does not have to take risks in this end in order to force a single by Sweden. Why risk your opponent possibly scoring two or three when it is unnecessary? Better to keep the play simple and ensure Norberg is held to either a single or a blank. So should Cheryl simply throw her last stone away, allowing Norberg to blank? It’s not inconceivable, though it would have appeared very strange to most observers. Depending on ice conditions and other factors, if she had made that call I would not have been too critical and would possibly applaud her. However, it is still advantageous to put pressure on your opponent, rather than concede the blank. As we saw, this did provide a critical steal at that stage in the game.

What about Norberg? On third’s first she chooses to hit the Canada stone just biting at the side of the rings, rather than play aggressively for a deuce. She could prefer to play for her deuce, knowing that if she’s held to a single her WP doesn’t change (in fact it goes up!). However, the risk of a possible steal needs to be evaluated. I’d prefer a draw here but likely Norberg is not aware of the numbers and wants to avoid being held to a single.

3. The Final: Canada (Kevin Martin) vs Norway (Thomas Ulsrud)
Nothing really to say here. Job well done by Team Canada and a well deserved victory. The semi-final appeared to have more tension early on but no real fear of an upset against Kevin Martin. Kevin has reached the pinnacle of his curling career and it will be interesting to see where he goes from here. He is still young (for a curler) and he’s always been committed to the game as a career, unlike most of his contemporaries, so would be surprising if he slows down at all.

Brier Preview
The Olympic Trial teams had built up a considerable record against each other over the previous years. The Brier does not provide us the same statistical detail in order to analyze probability of outcomes. What do we have?

We know Stoughton, Howard, Gushue and Koe have fought often, so let’s take a look at those results:

These numbers are interesting, but as always they only tell us part of the story:
• Gushue is 3-3 in last six vs Koe
• Gushue is 3-3 in last 6 versus Stoughton, but 0-3 in last 3. Gushue did win a significant game in Halifax against Stoughton in 2006, if you remember the 2006 Olympic Trials.
• Gushue is 2-4 against Howard since 08-09 season, including a big semi-final win at the Swiss Chalet National this past January.
• Stoughton is 2-7 in last 9 against Howard. One of those was a victory in the 2009 Brier semi-final.
• Koe’s lone victory over Howard was the 2007 Players Championship. Since then Glenn has won 4 in a row, all but one were close games including an extra end win in the Olympic Trials.
• Stoughton has won 4 in a row over Koe. Koe had won 3 in a row prior to that. Prior to that, 3 in a row for Stoughton, and prior to that 4 in a row for Koe!

I see these four teams a very close throughout the week. Gushue’s disappointment at the Pre-Trials is either forgotten or is motivating them to an impressive season, including a a Grand Slam win only 2 months ago. Is it perhaps their time?

Stoughton has looked very strong all year and is looking for redemption after their defeat to Howard in the Trials semi-final. Manitoba hasn’t won since 1999, and Alberta is catching up with 24 Brier wins, trailing the Buffaloes by only 2. Perhaps a transplanted Albertan, Kevin Park, will increase that margin to 3? I expect after seeing Martin win gold, he’d like nothing better than to return to the World stage where playing third for K-Mart he lost the final 19 years ago in Winnipeg.

Alberta’s Kevin Koe is poised and ready. They certainly know they can beat anyone here and are likely feeling as if it is their time. Third Blake MacDonald and Carter Rycroft are returning to the Brier, but Kevin himself is a rookie skip. The atmosphere in Edmonton during the Trials would have prepared them for this event so I don’t expect to see any nerves in front of the Halifax crowd this week.

Finally, Glenn Howard. Team Howard must have had mixed feelings watching Martin’s team stroll into the Brier opening banquet last night to a round of applause. Kevin gave a nice speech, but I wonder if Ontario was listening? The loss in the finals of the Olympic Trials surely still lingers, but this week provides a chance at redemption. This is also a team that likely should have had two Brier wins, after the upset in 2006 and a victory here will put them in the same conversation with Ferbey and Martin as top Brier teams of the decade. Unless of course 2010 is part of the next decade, in which case they will have a head start on the next ten years.

Predictions? Only that it’s unlikely anyone other than these top four teams gets a direct spot in the play-offs. New Brunswick and Saskatchewan are possible surprises, and could sneak into a tie-breaker. The rest is unknown. The Brier is where names are made and possibly there are a few to be made here this week. But in the end, one of these four will take the Macdonald Brier Tankard.


  1. This is terrific analysis - is there more analysis of the Women's Gold Medal match available? I'd be particularly interested in your analysis of the 9th, 10th and 11th ends. I was at the match, I felt Cheryl gets too much abuse for the last shots - what, for example, is the red stone doing there just below the house that kept Sweden's stone in play in the 10th end? Shouldn't Canada have cleared all the garbage away earlier trying to keep Sweden from 2 no matter what?

    Any insights into how the last 2 ends evolved would be really helpful. I'm STILL a bit heartbroken, the more I understand about the match the better I think I'll feel. Thanks!

    John Chmaj
    Sammamish, WA

  2. John, I intentionally avoided those ends. There isn't much strategic analysis to provide, it was much more about execution. Clearly Norberg's call in 9 is questionable, most any skip would draw - however Norberg, like Colleen Jones, knows her strength is her hitting ability so I don't challenge here decision. The shot you will make in that case is the correct call. In 10, Cheryl was unable to hit and stay on her first and, unfortunately, moved the stones around enough that Norberg was able to put pressure on her. It was a shot Cheryl will remember for some time and one she'd likely want back. In 11, the decision on Cheryl's first to peel rather than guard, is a centuries old debate which will rage on forever: if in trouble, when tied in final or extra end, do you peel on your first or draw? I don't mind her call as it appeared she couldn't block everything. Ultimately she left herself a shot that was perhaps 50/50 and missed it by less than an inch.

    It was game that, at different times, either team deserved to win or lose.

    It's a game that will be forgotten by almost all Canadian s within a few weeks, but one that Team Bernard will remember for the rest of their lives. I hope they cherish the incredible ride and the fantastic journey rather than focus on what could have been. In my mind, they were true champions.

  3. Thanks, again even this bit is helpful -- I believe a lot of us casual curling observers were drawn into a much deeper understanding of curling this Olympics. The number of televised matches along with the online access to all other matches allowed people to follow specific teams. That combined with the quality and consistency of Team Bernard throughout their run brought a whole new level of appreciation of the subtlety, grace and complexity of the sport.

    I've been casting about for anything with more than a cursory analysis of the gold medal match and your post was the only thing I've found other than a few match summaries. Just reading it has made me aware of another aspect of curling perhaps not fully appreciated - the skip has to make the same calculations, predictions of tendencies and probabilities as team manager, WHILE playing the game. In US football, for example, they have whole teams of people upstairs working through this on every play. On the sheet it's just the skip and his/her team. And even with the calculations you point out there's both an emotional flow to the match and the emotions of the skip herself to consider. When and how to put pressure, when to back off, how the other team will react, it's all in play as much as any stone.

    At the gold medal match, for example, the most extraordinary factor for me was unexpected: the EMOTIONAL intensity of it all. Neither team was giving an inch, and each shot had a focus and purpose that built to a tremendous climax. Having seen most previous matches it was easy to see Susan O' Connor was struggling early, and to know how critical her play was to any success. She found her touch and got better under pressure - very hard to do in ANY endeavor! When Norberg drew up to give up two I just about fell out of my chair - she may as well have thrown the stone onto the sheet next to her, that was the emotional impact of that!

    Anyway thanks again for taking the time to go into to all this - as you say most people will summarize this in their minds and move on, while I was left with this insight: victory is simple, defeat is complex! In victory the narrative is complete, one feels that regardless of what happened the end result was achieved and all inconsistencies fade readily to the background. In defeat every decision, every chance happening, the chains of events are examined, re-examined, down to ones' very soul! I hope and expect Team Bernard will use this to make themselves stronger, and hope to find another opportunity to see them, as they are truly a special team - doesn't take an expert to feel that! My 10 year old watched with me and he was able to pick up on all the power and richness of this fine sport, too.

    John Chmaj

  4. I like your site very much but estimates have no place in a mathematical analysis. You must replace each estimate with a mathematical probability of success based on the very statistics that you quote. In other words you will have to come up with a historical statistic to replace every estimate if you want to be taken seriously as a mathematical analyzer of curling. It is interesting that it is easy to prove with statistics that the odd/even end theory is bogus. Even Don Duguid subscribed to the odd/even end theory. Unfortunately present day curling commentators on TSN also subscribe to the theory. You can email me at At the last brier held in Ottawa, I had an article in the tankard times about the 12 things wrong with curling. My name is Alan Tomalty.

  5. Alan, thank you for your comments but I disagree. Estimates can always have a place. In poker, top pro players think very deeply at a mathematical level but also combine reading skills and intuition in order to come to a decision. Pure math doesn't work at the green felt and it won't work in any other sport, including baseball. Some "human" element is always there.

    Besides, I never want to be taken too seriously, so that solves your issue right there.

    I am not attemtpting to simulate curling, I am attempting to analyze on-ice thinking. On ice thinking will always have an unknown estimate "what do I think my chances are of making a certain shot?".

    Having said that....
    We just don't have the data available to examine the odds of top players making a "soft weight, through the port, tap back with an out-turn". We may be able to sort through some available numbers for more basic shots (draw around centre guard, nose hit, etc) - this would certainly add to the analysis. Perhaps Gerry and Dallas at CurlingZone would be able to crunch some of these. For now, I am very happy being taken "non-seriously" and hope that I'm moving the thought process a little further.