Building Gaps From Carry Medians

There is a particular moment in a fitting session that I have come to look forward to. The golfer has hit fifteen seven irons, the screen shows the shot list, and I turn it round and ask them which number they would put on a card. Nearly everybody picks one of the top three.

That instinct is completely understandable and completely wrong, and unpicking it is the most useful twenty minutes of the whole afternoon.

Why the Best One Is Not the Number

Your best strike of fifteen is, by construction, an outlier. It is the swing where everything happened to line up: centre contact, a clean lie, a tempo that did not rush. It tells you what the club is capable of in your hands under ideal circumstances, which is genuinely interesting information and completely useless for selecting a club on the twelfth hole.

On the golf course you are not choosing a club for your best swing. You are choosing for the swing you are about to make, which is drawn from the whole distribution of swings you own, most of which are not your best. If you set your yardages from the top of that distribution, you will come up short on the majority of your approach shots. Every golfer reading this already knows the feeling: the number says 155 and you are pin high maybe one time in five.

Average Versus Median

The obvious correction is to average the shots. That is better, but it has a problem of its own: an average is dragged around by extremes at both ends. One flushed shot that flew twelve yards past pulls the average up. One thin one that came out forty short pulls it down harder.

The median — the middle value when you sort the shots — is barely affected by either. Add one enormous outlier to a set of fifteen and the median moves by a yard or two, while the average can move by five. Since the whole point is a number describing a typical shot, and since typical is exactly what a median measures, the median is the right tool.

There is a second, subtler reason. Distance distributions are not symmetric. A golfer's shots are bounded above by physics and unbounded below by mishits, so the distribution has a long tail on the short side. In a skewed distribution the mean and the median genuinely disagree, and the median is the one that describes what happens most of the time.

How Many Swings the Median Needs

This is the question I get asked least and should get asked most. A median computed from six swings is almost worthless. We have tested this on ourselves: take a golfer, have them hit thirty seven irons, then compute the median of the first six, the first twelve, and all thirty.

Twelve is where the number stops being noise. Below that, two sessions a fortnight apart will disagree by enough to make any comparison between two clubs meaningless — and comparing two clubs is the entire purpose of a fitting.

For the driver and for wedges we want more, closer to twenty. Both clubs have wider strike variation than a mid iron, the driver because the club is long and the swing is fast, the wedges because partial swings and turf interaction add variability that irons do not have.

Discarding Shots, and When It Is Cheating

Every fitter discards some shots. The question is what rule governs it, and whether the golfer knows the rule.

Our rule is written down and stated at the start of the session: we discard a shot only if the golfer identifies it as a mishit before seeing the number. That constraint matters. If you look at the screen first and then decide it was a bad one, you are simply removing the shots you dislike, which is laundering rather than measuring.

In practice this removes about one shot in twelve. It is enough to strip out genuine misfires without quietly reconstructing the flattering distribution we were trying to avoid.

Spread Belongs on the Card Too

A median alone hides something important. Two golfers can both have a 155 yard seven iron where one is consistently between 150 and 160 and the other is anywhere from 138 to 168. Those are not the same club and they should not be managed the same way on a golf course.

So we print the spread beside every median — specifically the middle half of the shots, which is a robust measure that behaves well with the sample sizes we have. A golfer with a tight spread can attack a front pin. A golfer with a wide one should be aiming at the middle of the green and will save more strokes doing so than any equipment change would deliver.

What Rung Spacing Actually Works

Once you have medians you can look at the gaps between them, and this is where the ladder either holds together or falls apart.

Our working rule is a minimum of about seven yards and a maximum of about fifteen through the middle of the set. Closer than seven and the two clubs are duplicates; you have paid for a decision that does not matter. Wider than fifteen and there are distances on the course you cannot cover with a full swing, which forces manufactured three-quarter shots at exactly the wrong moments.

Both ends of that rule are negotiable for individuals. A golfer with a very repeatable strike can happily live with six yard gaps in the scoring clubs. A high-speed player may accept eighteen yards between their longest two clubs because the alternative is carrying something they cannot use. The rule is a starting frame, not a law.

Normalising for the Day

One last thing, and it is the one most fitting reports omit entirely. Carry depends on air density, and air density depends on temperature, pressure and humidity. A session run on a cold February morning and a session run in humid July produce systematically different numbers from the identical golfer with identical clubs.

Every ladder we print states the air condition the numbers were normalised to. Without that statement, comparing a card from last winter against one from this summer is comparing two different experiments and pretending they are the same. It costs nothing to record and it is the difference between a document that ages well and one that quietly becomes wrong.

The Short Version

• Use the median of tracked carry, not the best shot and not the average.
• Twelve swings minimum for irons, closer to twenty for driver and wedges.
• Declare your discard rule before the golfer sees any numbers.
• Print the spread next to the median. It changes how you play the shot.
• Aim for seven to fifteen yards between rungs, and know why when you break the rule.
• Record the air condition you normalised to, or the card expires without telling you.