Estimating Scores for Holes Not Played – Another Bad Idea from the World Handicap System

 The trouble with the World Handicap System (WHS ) it that its administrators do not know how to leave well enough alone. Too often the WHS confuses motion with progress.  Case in point is how a “hole not played” is now scored for handicap purposes.   Prior to 2024, if a hole was not played the player simply entered a net par.  It could be argued that the net par procedure is unfair.  For example, if the stroke allocation of a par five is 13, all players with a handicap between 0 and 12 would record a 5.  In actuality, however, the 12 handicap is likely to have a higher score than the 0 handicap.   To correct this inequity the WHS adopted a procedure for holes not played as summarized below.

1. An expected Score Differential for the hole or holes not played is calculated, based on a given Handicap Index and a course of standard difficulty. The expected score is based on the average Score Differential of a player with a given Handicap Index and a normal distribution of scores – so it is not specific to each player.
2. A Score Differential for the holes played is calculated using the player’s actual scores and the rating value of the holes played.
3. The Score Differential from the holes played is combined with the expected Score Differential to produce either a 9-hole or 18-hole Score Differential.

To use this procedure, a player must enter all of his scores on holes played which is both time consuming and laborious.   The WHS argues that this procedure will lead to more accurate Handicap Indexes.  The WHS, however, does not supply any evidence for this claim.   

To examine the claim of increased accuracy, the estimated hole score is compared with the net par score to see if there is a significant difference between the two.   The WHS does not give a clear example of how the missing hole score is estimated.  For the purposes here the Estimated Hole Score is found by the following formula:[1]

Estimated Hole Score = (WHS Differential) x (Slope Rating/113) +(Course Rating - S17)

Where,

              S17= Player’s score on the 17 holes played

A small sample of scores from a tournament where a par five with a stroke allocation of 13 was out of play is used.  The expected score[2] and the net par scorer are shown in Table 1 below:

Table 1

Estimate Hole Score Versus Net Par

Player’s Index	Course Ratings	Net Par	Estimated Hole Score
7.1	70.0/124	5	5.0
7.7	71.2/127	5	5.2
12.0	70.0/124	5	5.4
16.4	70.0/124	6	5.7
19.9	68.4/120	6	5.7
38.0	70.3/124	7	7.2

 

While the sample is small, it does show that the estimated hole score from the same set of tees does increase with a player’s Handicap Index.  It also shows, however that there is usually a small difference between the Net Par Score and the Estimated Hole Score.

What is important is how the Estimated Score affects a player’s Handicap Differential in comparison with the Net Par Score.  Table 2 below shows the Handicap Differential using the WHS Estimated Score and the Net Par Score.  

Table 2

Handicap Differential for WHS Estimated Score and Net Par Score

Player’s Index	WHS Diff.	Net Par Diff.	WHS – Net Par
7.1	4.6	4.6	.0
7.7	6.2	5.8	.4
12.0	12.2	11.8	.3
16.4	13.4	13.7	-.3
19.9	16.3	16.6	-.3
38.0	37.3	37.1	.2

 

There appears to be little difference in the Handicap Differential between the two procedures.  If the score was not among the best 8 of 20 scores, both procedures would have the same effect on a player’s Handicap Index—none.  If it was among the best differentials, the largest effect among the six players caused by the WHS procedure would be to increase a player’s Handicap Index by 0.1 (.4/8 round up) at most.

The WHS was probably forced to adopt the Estimated Hole Score since it adopted the Estimated Nine-hole Score—another bad idea (see www.ongolfhandicaps.com, The World Handicap System Predicts Future Performance, January 25, 2025.  The thinking would be along the lines that if the WHS can predict the scores on nine holes, it would be inconsistent to believe it could not predict the score on one hole.

Is such a small difference in a Player’s Handicap worth the effort?  The WHS should present evidence that the estimated hole procedure is more equitable.  It should also present a research paper describing the statistical theory behind the theory.  The WHS has a tradition of not making its research public to avoid peer review.  It relies on the golf community to believe in the omnipotence of its decisions.  It has worked so far.

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[1] This formula produces the differential shown in a player’s GHIN file.  It is not clear how the WHS actually calculates the Estimated Hole Score.