Mixed Strategies in Challenging: Tennis Edition


[Archived from: The Sports Economist, 29 January 2012]

Played last night into early morning, the epic almost six-hour, five-set Men’s Singles Final of the 2012 Australian Open between top two seeds Novak Djokovic and Raphael Nadal will be long-remembered by tennis purists for many reasons.

For economists, however, one relatively minor incident may just stand out, if for nothing else as a game-theoretic oddity: Nadal challenged the call on his own serve [watch footage], which had been ruled in by the line judge (and not overruled by the chair umpire), ostensibly because Djokovic rifled a rapid-fire winner in return, at a not-so-critical moment in the second set…and it almost worked to earn a replay of the point for him, as Hawkeye ruled the serve to be in only by a hair’s breath.

Of amusement is how neither of the host broadcaster commentators Lleyton Hewitt nor Jim Courier  (both former world number ones) appeared to know whether this was indeed permissible under the current rules of the Challenge System, especially since the former is still a tour professional (he had bowed out in four sets to Djokovic in the fourth round). Fortunately, the chair umpire knew better, although Djokovic protested briefly on the basis that it took Nadal too long to indicate the intention to challenge, however, given the (weak in one’s opinion) standards of enforcement of time limits to indicate, the chair umpire was probably correct in allowing it.

Perhaps it worth wondering whether ITF officials and collaborators foresaw this (and other hitherto unobserved unusual scenarios) when drafting the specifics of the system, and indeed whether in light of this occurrence they will decide to ‘close the loophole’, though I’d doubt it, since there seems to be nothing fundamentally wrong with this type of challenge in principle.

Since less than half of all challenges currently are upheld, if there is a reform worth considering, it would be the limiting of challenges to two (incorrect) per set, as originally in the 2007 Australian Open, to reduce the number of more frivolous and tactical challenges, which appear to have been rising in incidence more recently as players have become more used to – and more able to exploit – the system.

Hottest 100 on ‘ABC News Breakfast’


I appeared on ABC News Breakfast again this morning, but not the newspaper segment as previously. Rather, I was discussing my Hottest 100 project (details below), with Paul Kennedy and Melissa Clarke.


Liam Lenten interviewed on ABC1 News Breakfast about his study (with Jordi McKenzie, U Sydney) on voting biases in the Triple J Hottest 100, on the day before the results of the 2011 installment are counted down on the youth radio network.

The First Two Data Points Say “…mmm, I’m Not Sure Yet”


[Archived from: The Sports Economist, 23 January 2012]

The new NFL overtime rule, see page 111 (introduced last season for playoff games only) finally became binding in the current playoff series two weeks ago, and then for a second time yesterday. Of most interest to economists about the rule change is its potential for teams to alter their overtime strategies in response to the element of the rule that both teams are now guaranteed a direct opportunity to score.

While it’s far too early to make firm inferences about this, it’s worth recounting that the primary intention of the rule was for the result of the coin toss determining which team gets to receive the kick-off (and consequently first possession) to have less power in determining the match winner (previously almost 60% of the nearly 500 overtime games since 1974). At the margin, we might also expect touchdowns to be the winning method of scoring slightly more often than previously, since it is now the only way that the team with first possession can effectively kill the game without the opposition getting the chance to equalize.

On the basis of these first two observations, it is interesting to note that the qualitative outcomes were very different – while winning the toss allowed Denver and Tim Tebow to end the contest on the first play via a touchdown, both NY Giants and San Fransisco each failed to score on their first possession, triggering reversion to sudden death as previously, which was won eventually by the former. [Disclaimer: I have only recently followed the sport, so feel free to critique this via comments.]

While this (admittedly premature) anecdotal evidence suggests that the coin toss is more influential than before, the reality is about as mixed as could have been expected. Someday – perhaps in a few decades or even within the decade should the rule be extended to the regular season, one of our esteemed TSE colleagues will no doubt crunch the numbers on this rule change when there is a sufficient (presuming due restraint exercised) sample size.

NFL Even MORE Competitively Balanced (Yet Again)


[Archived from: The Sports Economist, 3 January 2012]

Further to an earlier post one year ago to the day, the same result occurred upon conclusion of the 2011 NFL season as in EVERY previous season since the re-alignment to 32 teams in 2002 – that the  NFL is even more competitively balanced when the standings are adjusted for strength of schedule (than on the basis of raw standings) .

Even though this season was noticeably less balanced than (the recent) average without adjustment, the difference from the adjustment was even more pronounced than any other season during this period (with the exception of 2003), making adjusted competitive balance about average over the same period.

On this occasion, the actual-to-idealized standard deviation ratios are 1.611 (unadjusted) and 1.462 (adjusted); the Gini coefficients are 0.292 (unadjusted) and 0.260 (adjusted); and the Herfindahl indexes of CB are 1.162 (unadjusted) and 1.134 (adjusted).

Ultimately, this result reinforces further the need to account for strength of schedule in producing standard competitive balance metrics for various empirical studies!