WHS (UK) Explained

Disclaimer

The content of this blog is entirely my own opinion/interpretation and is probably considered heretical and possibly factually incorrect by the UK Home Golf Unions. But in the absence of a public specification we mere mortals can only try and reverse engineer both their thinking and algorithms. Should anyone from the Home Unions want to correct my interpretation then feel free to contact me. I am always happy to correct errors, but I will not take a blog down.

OK. So what is WHS ?

It is supposed to be a World Wide Handicapping system that ensures we all play off a transferrable handicap that can be used to ensure fair games played at any course in the world by any mix of handicapped players from different clubs and countries.

The rest of the world have been using it for some time now, so it should have been a simple task to create a matching system for the UK, shouldn't it !

Why change anyway when the old handicap system was not broken ?

That is a matter of opinion !

If you just played at one club, or always with the same mates, then the old system worked well. However as soon as you start playing inter club matches or in other clubs Open's then you would have recognised that he old system was broken.

Over the past 10 years I have played in a fair number of inter-club matches where my standard of play has been questioned. I do not consider myself a bandit. So I put this down to the intrinsic difficulty of my home course being a lot harder than many other local courses. The only defence that the old system of handicapping had against this was the single measure of course Standard Scratch Scores, SSS, and to be honest this was just not up the job of levelling a field of players from different clubs.

So I agree that some kind of change would have been beneficial.

Was moving to a UK customised version of WHS the right change is whole other question.

So how does WHS work ?

It is not simple that is for sure !

In designing a handicap system first you have to consider the main variables, these being - The Courses, the Players and the Playing Conditions.

Courses vary dramatically in design and difficulty, high handicap players play their second shots from parts of the course that low handicap players will never visit ! Add high winds, rain, mud, frozen greens and scores will rise. Warm weather and hard fairways mean longer shots and scores will plummet. So a lot of variables to consider.

Once you have designed your system, you need to test it. Fortunately there is an abundance of data available - certainly all of the competition scores from all of the clubs for the past 8 years or more. So WHS could design and test their system against real world data and compare the results, then if necessary adjust the algorithm to make it more accurate.

Read on MacDuff......

First - How do you rate the difficulty of one course against another ?

Answer - You don't. Instead WHS invented a mythical standard golf course against which each real world course is then compared.

We already know that a single SSS measure did not work. So what WHS decided to do was to double this up to two comparison measures to determine the difficulty that any real world course presented.

1 - The first measure is the "Course Rating".
On a perfect day how well would a scratch player from our mythical standard course play your home course ? This difference is your home courses "Course Rating" and is an updated version of the old system's Standard Scratch Score. Under the old system my home course, played off the White Tees, had a SSS of 72 and a Par of 71 or +1.0 difficulty. Under WHS this is now assessed as +2.7 i.e. a standard course scratch player would on average play 2.7 shots over par here.

2 - The second measure is the "Slope Rating"
This is a number that indicates the relative difficulty of a set of tees on the golf course for a bogey golfer (think 18 handicapper) from our mythical standard club in comparison to a scratch golfer. i.e. how many shots over the Par +Course Rating would an 18 handicapper typically score on that course.

WHS turns the scratch and bogey players scores into two points on a line graph and draws a sloped line between them, so that we can now extrapolate the predicted scores of all the other handicaps.

The Score Number returned by the above graph's are effectively the players "Course Handicap" on that course/tee set.

Course Slope Ratings vary in the range from 55 to 155, with our mythical standard course having a rating of 113.

Why 113 ? We do not know. It certainly does not represent any kind of average course in my local area, as I know of only 1 course that has a 113 rating - the average of the 40 nearest courses to my home course is roughly 125.

Why not use 100 ? This would reduce the possible differentiation between course's by 13% but it would simplify the maths and make it far more understandable.

Secondly - How do you compare players ?

A individual players scoring ability is measured by their Handicap Index. To gain a Handicap Index a new player must submit a minimum of 3 qualifying cards to their club's Handicap Secretary.

Under WHS all players are given a calculated Handicap Index , based on the results of their cards returned. The Index represents the handicap to which they could play on the WHS mythical standard golf course, not their home course. See the WHS Calculation Section below...

Before you can play on any real course, including your home course, you have to use this theoretical course Handicap Index to calculate a real world Course Handicap given the rated difficulty of that real world course. This Course Handicap will represent how many extra shots you need to play that real world Course in Par.

In the Rest-of-the-World this calculation is:

Your Course Handicap = (Handicap Index x (Slope Rating/113) + Course Rating) {rounded to the nearest whole number}

In the UK this calculation is "simplified" to:

Your Course Handicap = Handicap Index x (Slope Rating/113) {rounded to the nearest whole number}

Note: Under WHS-UK the Course Rating is handled in the post round competition handicap calculations and not upfront.

Fortunately there should always be a Handicap Index to rounded up Course Handicap conversion table displayed either in the Pro Shop or on the 1st Tee of all Courses.

Unfortunately the calculations do no stop there. In the UK we must apply a further Competition Allowance adjustment made to the rounded up Course Handicap to give you your Playing Handicap ! This Competition Allowance varies by the Competition Format, but is fixed by the Home Unions for both Stableford and Medal Competitions as 95% of the rounded up Course Handicap (not the exact CH) and then the exact Playing Handicap is itself rounded up.

Note: I have seen that a Competition allowance may also be applied to some competitions in the ROTW - more research required !

If you use your Clubs Competition Terminals or the phone App provided by your Clubs Software Vendor, e.g. IntelligentGolf App or CSI's Club2000 App, then that does all the work for you and will tell you your current Playing Handicap when you sign in for a competition.

Thirdly - How do you evaluate the Playing Conditions ?

The old system had Competition Standard Scratch, CSS. That system looked at the mix of players playing in any competition and their scores (i.e. the percentage mix of each different handicap division competing in that competition) and then used a massive lookup table to calculate an adjustment for the playing conditions on that day. That table having been generated from a lot of historical data. That course playing conditions adjustment was added to the courses SSS to generate the CSS, for that day. This seemed to work well up to it's programmed limit of a +/- 3 shot adjustment, but in my experience failed whenever the wind got up when the maximum adjustment of +3 was just far too small !

Now I would assume that there was little need for a wholesale rewrite of this, and that the new adjustment for Playing Conditions Calculation, PCC, is similarly based on historical data.

However the Home Unions have once again decided to hide the calculation and its' programmed limits, from the public, and this time round I am not going to waste my time trying to reverse engineer that one.

The WHS Calculation.

I have spent a fair few days in the past month reverse engineering how WHS works and then comparing it to my own handicap record to make sure that I got it right.

If you have played more than 20 qualifying rounds, and your handicap is not rising rapidly, then your WHS Index is simply the average of your 8 best Score Differentials in the last 20 qualifying rounds. Using an historic average calculation means that your handicap can now change quite dramatically and strangely after every round. As you both add the latest score and discard an old score at the same time both of which effect the outcome of the handicap calculation.

Your latest round's Score Differential will replace the oldest (now 21st) round differential in the 8 from 20 calculation. But a poor differential in the latest round that is actually a better differential than your old 8th best round can result in a lower Handicap Index. Similarly what you might consider as a good latest differential, if the 21st round differential being discarded was actually better than your latest round, may occasionally result in a new higher Handicap Index.

So what is a Score Differential ?

If you log on to the England Golf Web Site (do not use the England Golf App as that only contains summary data so is just a waste of memory on your phone) and then look at your "Overview" you will find a table with a row of numbers for each round recorded. The numbers shown in each row are used to calculate the Score Differential for that round.

The Adjusted Gross column is the Total of your individual Hole Scores + No Return (NR) adjustments

Each NR on the card scores = par score for that hole + ”Players Handicap allowance on that hole” +2

For handicapping purposes each hole has a maximum score equivalent to this NR score, regardless of the actual score on the card.

If a round is one of the 8 best used to calculate your Handicap Index then on the England Golf graph the Adjusted Gross number has a green spot next to it.

The Playing Course Condition column is basically the new name for the old Competition Scratch Score, CSS adjustment, see the PCC section above.

The Score Differential column is your Adjusted Gross score compared to the Course Rating (not Par) for the Tee played, corrected for the Playing Conditions and then normalised to the mythical standard course using Slope Rating) using the following calculation:

ScoreDifferential = (AdjustedGross -CourseRating -PCC) * 113 / SlopeRating

The WHS Index Column is simply the Handicap Index that you started/played that round with and it is not your new Handicap Index as that is now shown to the right of the graph above the Overview Table.

What if my handicap is rising rapidly ie What are "Caps" ?

WHS uses a combination of a Soft Cap and a Hard Cap to limit any automatic upward movement of a player’s Handicap Index to a maximum of 5 shots within any 1 year rolling period.

After each new card is entered WHS will calculate a players new Handicap Index (HI) using the average of the best 8 scores from the last 20. WHS will work normally when calculating a players new Handicap Index up to a 3 stroke increase above the players Lowest Handicap Index (LHI) for the previous 365 days.

If the calculated new Handicap Index compared to the players Lowest Handicap Index is greater than 3.0 shots this will trigger the use of one or both Caps to restrict any large increase to the players Handicap Index.

If a player has had a 3 stroke increase above their Lowest Handicap Index then a Soft Cap will be used to slow any subsequent increase to 50% of the normally calculated increase in their Handicap Index.

A second Hard Cap will then stop any upward movement above a maximum of 5 strokes over the 365 day Lowest Handicap Index.

Unfortunately the initial implementation of WHS is a little flawed, in that it totally ignores your pre-WHS handicap in setting the initial Handicap Index. As my (20th) oldest card submitted was by far my best round the calculated Lowest Handicap Index is actually significantly lower than any pre-WHS handicap that I have held in the past year. I have been recovering from surgery so my game is not as good as it could be and my handicap has increased significantly. The initial LHI calculation is currently costing me an extra shot, but hopefully it will all sort itself out next September.

What is all this 95% Stableford/Medal Malarky ?

I must admit that there is a good chance that I may have got this wrong when I first wrote this blog. I have subsequently found a statement on Facebook that the WHS Handicap Index calculation ignores any Competition Allowance and calculates your Score Differential for each round as if you had played off your full Course Handicap.

Whilst the comment would makes sense, I have been unable to validate it.

Looking at my last Stableford competition the 95% Competition Allowance reduced me from 26 shots to 25 so I lost a second shot on Stroke Index 8. I happened to NR that hole. So if WHS was using the full Course Handicap then I would have expected the adjusted gross score for that hole to show Par 4 plus 2 shot handicap plus 2 for an adjusted score of 8. But the England Golf Overview page shows a 7 has been used for the handicap calculation. Suggesting that they are, by design or error, actually using the 95% for handicap purposes. Which makes little sense as it will in the long term drive my handicap up by a shot defeating the initial purpose.

So what else could the 95% be used for ? The only effect it has, is to reduce the chances of higher handicappers winning a competition. Ostensibly to provide a better/fairer distribution of competition prizes, though as most clubs split the prize pots into handicap divisions that argument is pretty much invalid. So it probably just comes down to an attempt to reduce the odds of a high handicapper winning a Trophy/Majors/Board competition.

How is the UK's implementation of WHS different from the rest of the world ?

When you roll up to play on a course in the Rest of the World the Ratings Board on the 1st Tee shows you the result of the playing handicap calculation allowing for both Slope Rating and Course Rating. In the UK despite the heading on the boards saying Slope and Course Adjustment, they actually only show the calculation for the Slope Rating and ignore the Course Rating. In the UK the Course Rating is only applied after the round in the post competition handicap adjustment calculation.

This should have minimal effect on a competitions outcome as every player would get those shots, basically it just reduces everyones reported Stableford score.

Long term this should also have minimal effect on your handicap index. But, as the rounding up of numbers for the Course Handicap is now done in a different place, on any one day depending on how close your actual exact Handicap Index plus Course Rating is to the rounding point it can effect the actual number of shots you receive by + or - 1 shot.

Why is the UK's implementation of WHS different from the rest of the world ?

Bloody good question ! Answers on a postcard to England Golf please...

What went wrong with the WHS Roll Out ?

Despite having many years to implement this system, the roll out has demonstrated that there has been inadequate testing a) with the initial data migration and b) integration with the existing handicap vendors systems. The home unions inability to handle the volume of calls from the Club Handicap Secretaries, reporting errors, also demonstrates their lack of adequate resource planning.

With a background as a Software Development Project and Program Manager I am very familiar with the kind problems this Project could have without adequate test planning and execution. I would love to see the post project lessons learnt documentation, if they bothered to create one.