Tips for Tipping


You've been forced to enter a tipping competition for a sport you know nothing about and, frankly, have no interest in adding to the list of sports you know something about. The competition is standard in that it rewards you with 1 point for a correct tip and no points for an incorrect tip. Your 15 minutes of research, which represents the entirety of the time you're willing to spend on the endeavour, reveals that the home team consistently wins about 58% of games season after season.
Given that knowledge, which if any of these three strategies is superior:
  1. Match the expected home team/away team mix in your tips, that is, tip the home team 58% of the time
  2. Recognise that you have no basis on which to favour one team over another so tip the home team about 50% of the time
  3. Be lazy and always tip the home team
Make a mental commitment to your answer and try to come up with at least an intuitively appealling logic for it.
Option 1 has much to recommend it. If nothing else it means that you'll tip home teams about as often as they tend to win (and, consequently, also tip away teams about as often as they tend to win). Following this strategy you can expect to be right 0.58 x 0.58 + 0.42 x 0.42 = 51.3% of the time. Well that is better than chance.
Option 2 is now looking a little sick. Using it, you can expect to be right 0.58 x 0.5 + 0.42 x 0.5 = 50% of the time. That's worse than option 1, so scrub this strategy from the list.
Option 3, as it turns out, reigns supreme amongst this set of options since it will make you right, on average, 58% of the time. Surely that'll be enough to convince some people to believe that you know quite a bit about the sport.
Bear this analysis in mind when you're reviewing the tipping performances of the experts in the papers during the season ahead. The figure of 58% is about right for the proportion of home teams that have won recently in the AFL (if you count draws as one-half a correct tip - it's a trifle lower if you count them as losses). The figures for the past four seasons are:
  • 2006 - 58.4%
  • 2007 - 58.1%
  • 2008 - 57.3%
  • 2009 - 57.8%
Actually, even if the expert you're looking at is tipping at better than 60%, that performance still isn't particularly impressive because, in the AFL, there's an even better strategy than reflexively tipping the home team, though its historical performance has been more variable. That strategy is to pick the favourite. Overall, they've won about 65% of the time since the start of 2006. The individual figures for each season are:
  • 2006 - 64.3%
  • 2007 - 64.6%
  • 2008 - 72.0%
  • 2009 - 65.9%
This pick-the-favourite strategy has another endearing feature to go with its sterling performance: it works well from round 1 of the season. For the first four rounds of seasons 2006 to 2009 the strategy has tipped at 68%, and for the first eight it's tipped at 66%. In contrast, a pick-the-home-team strategy has fared badly in the first four rounds of these same seasons, landing only 52% of winners.
So this year, if you insist on trying to out-tip the guys whose salaries depend on their tipping prowess, whenever you're unsure about a tip just plump for the favourite.