Tuesday, 24 January 2012

Field Strength Metric/Charts added to Golf Predictor

Portion of new 'Tournaments with Field Strength' page showing the start of the 2011 season.
Field Strength section of Tournament page, showing new metric (2011 Players Champ.)

I am excited to announce the addition of a new "Field Strength" metric to Golf Predictor. This useful new statistic has been developed following a user inquiry and is a measure of the tournament field quality. The algorithm used to calculate this new metric depends on two main factors, namely the world ranking distribution of the field and the field size. Other points to note on this new metric include:

  1. The end value is expressed as a percentage.
  2. Small field sizes will have a significant effect on the end value.
  3. A field strength of 100% would represent a full field (over 150) with no (or hardly any!) missing players from the top of the world rankings. e.g a field of 156 made up of all the players from the top 156 in the world rankings). Unlikely to ever happen!
  4. The lowest field strength possible using this new algorithm is about 25%*. This corresponds to a field of 20 or 30 with no one in the world's top 1000. Unlikely to ever happen either!
  5. Like the other world ranking statistics on Golf Predictor, this new metric is based on the entry list for each tournament. This is because world ranking information is stored only as part of a golfer prediction. This in turn is dependent on whether the golfer was in the entry list (including any alternates) or not at the time the predictions were generated.
  6. Because of the above, alternates and some other golfers in the entry list may not actually play in the event. Similarly, late entrants to an event will not have a prediction record, so their rankings will not be included in this metric.
  7. European PGA Tour events tend to have far more alternates than US PGA Tour events. Since alternates are usually lower ranked golfers, this can skew the field strength metric towards the low side for some European events. However, this is largely mitigated by the increased field size resulting from these alternates, which usually results in a higher field percentage.
  8. The exact field for many of the bigger events (e.g. majors, FedEx Cup events and most WGC events) is known ahead of time. Thus, alternates are usually only an issue with regular tour events.
  9. This metric is only available for tournaments that have been predicted by Golf Predictor. This means the last three complete seasons (2009-11) and most of the 2008 season (from The Masters on and a couple of earlier events).
  10. All the predicted tournaments outlined above have been updated in the system with this new metric.
  11. While the algorithm itself may be somewhat arbitrary, the relative values are an accurate reflection of the field strength i.e. the higher the end value, the better the tournament field and vice versa. 
  12. This new metric is a much better indicator of field quality than the average WR of the field, which was the only statistic available hitherto now on the site to gauge field strength.

This new field strength metric reveals some interesting statistics about the relative quality of tournament fields on both the European and US PGA Tours. It has also resulted in a number of significant changes to the system:

  1. There is a new 'Tournaments with Field Strength' page available from the Tournaments option ('View Options' menu). This page also shows the average field strength for the selected season/tour. This is shown in the first screenshot above, which shows the start of the 2011 season.
  2.  The 'Field Strength' section of each 'Tournament Details' page has been amended to include this new metric (second screenshot above).
  3. Four new charts have been added to the 'Tournament Statistics' page. The existing best and worst fields charts for each tour have been amended to use this new metric and the graphs they used to show have been renamed to 'Best/Worst Ave. WR'.
  4. The existing field strength charts on the main prediction page and the 'Field Strength' section of each 'Tournament Details' page (pop-up version) have been updated to include this new metric.

These four new charts bring the total number of charts on the site to 259. However, like all the changes outlined above, these charts are only available to subscribers. So, sign up today to get the most out of Golf Predictor, the premier US and European PGA Tour statistics site.

*The reason that it would be as high as 25% is that all golfers outside the world's top 1000 are assigned the same WR of 1050 by the system. This means the standard deviation of the WR distribution would be zero, which would inflate the final percentage somewhat. This could be allowed for, but it is extremely unlikely ever to happen!

1 comment:

Golf Predictor Guru! said...

Since tee-off groups were added to the system in May 2013, the field strength should be more accurate after the Tuesday of a tournament week. This is because all alternates will have been removed from the system.