I am sure you know that Golf Handicaps are calculated for 18 hole rounds. But did you know that if you only play 9 hole rounds you would have a Handicap Index called N?
You will see in our Trends section that there are a set of “9 Hole Rounds” graphs. In there you will be able to see your Handicap Index N which is calculated using your 9 hole rounds. (it won’t show if you don’t have any 9 hole rounds)
To calculate this handicap you simply use the course rating of the 9 holes you played and use the same formula you use for 18 hole Handicaps. You will see that this handicap ranges from 0-18 instead of 0-36 like the regular Handicap Index.
NOTE that 9 hole rounds are not utilized for the regular Handicap Index calculation.
Why not simply multiply your score times 2 for 9 hole rounds?
Well, the USGA doesn’t really explain the reasoning behind having two different handicaps but based on all my readings and interpretations of the USGA thinking, I will give you my best guess. (so please interpret this post as my opinion and not the USGA’s)[like_to_read][/like_to_read]
“Playing 9 hole rounds requires different level of concentration than 18 hole rounds. Keeping the focus for 18 holes (~4.5 hours) is much more difficult. So it wouldn’t really be fair to multiply by 2 the score and then get the equivalent 18 hole round score.”
But I figured you wouldn’t believe it so I ran a couple of analyses, here they are!
What would be my handicap if I calculated front and back nine separately?
We looked at 5 different golfers, and while there is only significant difference in 2 of them, it is; in my opinion, enough . See the graph below comparing the handicaps of 18 hole rounds versus the handicap calculating every 9 holes (multiplying by 2)
Look at golfer 1 and golfer 5. There are ~4 points difference between the regular handicap and the equivalent handicap we calculated using their 9 hole rounds. And out of the 5 there is only one of them that have less than 1 point difference.
What is the average difference between the front and back 9 per round?
We looked at the front 9 and back 9 of the same 5 golfers. We found that the difference between the two average 4.2 strokes. That means that on average, those golfers had a 4 strokes difference between the front 9 and the back nine. So, if one of this 5 golfers shoot 44 on the front 9, he was expected to shoot a 40 or a 48 on the back 9. That’s a lot of strokes since 4.2 would mean a 8.4 difference on a 18 hole round.
I know that this is not enough statistical proof and that we would have too look at a larger sampler. But I do believe that it is a lot easier for the regular golfer to shoot a 41 on 9 holes than it is to shoot an 82 on 18 holes. So you be the judge, but I think the USGA is right in separating the two and having a Handicap Index (18 Holes) and a Handicap Index N (9 holes).
What do you think?
Enjoy your golf!