Data in Golf: Face Impact Dispersion

Welcome back to the AE Golf Performance Newsletter! It’s been a busy few months, so I have not had as much chance to write new posts as I was hoping. But I have recently been doing a lot of work with golf data, and believe there are some useful topics to touch on.

Data Availability in Golf

Golf is in an exciting place from a tech and data standpoint. The availability to tools and technologies have made data more accessible than ever. This includes launch monitors, on-course shot tracking, motion capture, force/pressure plates, and more.

One of my interests is helping golfers and coaches use technology and data more effectively within their specific setting. This involves not only understanding the outputs coming from tech or other feedback sources, but how to process and act upon the information from that output.

Navigating the natural shot-to-shot variability in golf is a key to effective use of data/tech. You will hit great shots, and you will hit poor ones. Overreacting to any individual shot is usually not helpful. Rather, thinking in terms of patterns, tendencies, and probabilities can account for this variability and make better decisions.

Today, I want to focus on patterns in relation to impact location on the club face. Where you strike the ball on the club face affects multiple aspects of how the ball will fly, and is an important feedback source you can be collecting during practice or play. Understanding your tendencies across multiple shots and/or under different conditions can help identify what to focus on and whether practice is translating to meaningful improvements over time.

The Importance of Club Face Impact Location

Where you strike the ball on the club face directly influences the resulting launch and flight of the golf ball, affecting both distance and accuracy of the shot. This is driven by several factors. I’ll just summarize a few of the basics here, but let me know if you’d like me to dive deeper into the topic later on:

1. Strikes closer to the club’s “sweet spot” result in more efficient energy transfer from club to ball. So an off-center strike can directly influence the ball speed at a given clubhead speed.

2. Strikes away from the club head’s center of gravity cause the face to “twist” in response to the impact. This occurs in both the vertical and horizontal direction. Notably, this causes a “gearing”, or counter-rotation on the ball which can influence how the ball spins (particularly with clubs where the center of gravity is further from the surface of the club face, like modern drivers).

3. Modern drivers and woods often have roll and bulge on the face. The effective loft of the club is higher towards the top of the club, and lower at the bottom. Additionally, shots struck towards the toe tend to result in a more open face angle and vice versa for shots struck off the heel.

As a result, impact location can affect ball flight in a few ways. For example, if all other impact factors are equal:

• Strikes low on the face tend to launch lower with more spin, while strikes high on the face launch higher with less spin.

• Shots towards the toe of the club tend to start further to the right and curve more to the left (more negative spin axis), while heel strikes start further left and curve more to the right (more positive spin axis) for a right handed player.

• Shots further from the “sweet spot” will have lower ball speed at a given swing speed (e.g., lower smash factor or efficiency).

There are many factors at play, such as the type and design of the club being used. But for now, the main idea is that face impact location matters. And not just for the obvious reasons (e.g., it influences distance and accuracy), but also because it influences your interpretation of other impact or ball launch data you collect from that shot.

For example, you could present the club in a way that you’d expect to promote a draw (e.g., club face slightly closed to club path), but end up mitigating that draw flight by striking it off the heel of the face. But that’s a topic for another day. Let’s move onto the concept of face impact dispersion patterns.

Face Impact Dispersion Patterns

Because of the importance of impact location, it shouldn't be surprising that skilled golfers tend to consistently strike the center of the face more often than less skilled golfers. For example, I found data from multiple research studies (e.g., Betzler et al., 2012; Jones, 2019) that compared driver impact locations across skill levels (Category 1 = highest skill, Category 4 = lowest). I then ran a simple simulation of 400 shots from each category to give a visual comparison of handicap categories. As skill level decreases, the face impact dispersion pattern increases in size.

While this simulated data is nice for visualizing general differences, individual golfers tend to have tendencies or biases in terms of where on the club face they strike over time and under different conditions. For this reason, I like to create impact dispersion patterns for individual golfers, which can be used to:

1. Identify tendencies (e.g., consistently striking low on the face).

2. Monitor progress or changes over time (within or across sessions)

3. Compare strike quality under different conditions or situations (e.g., on the driving range vs course, or when swinging at a high effort level vs lower effort levels).

4. Provide feedback within sessions to help drive quality practice.

Some examples from 9 different golfers are seen in the figure below, where there are clear differences in both how closely the impact locations are clustered as well as their tendencies in terms of where on the club face they tend to strike.

How tightly the data is clustered gives an indication of consistency across swings in terms of face impact, while the distribution of the impact locations can give insights into the golfer’s tendencies. From there a golfer can use drills or practice to try to improve their overall pattern over time.

Importantly, we can use a combination of visual and statistical methods to look at changes in dispersion pattern across sessions. This could include any number of comparisons depending on what your goal is:

• Comparing one session to another (is my dispersion pattern different today than a previous day?).

• Comparing strike quality under different conditions (e.g., what happens to impact location when swinging different clubs, at different effort levels, on the course vs off the course, when doing block practice vs variable, etc.?).

• Changes within a session: has your ability to strike the center of the face changed from the start of a session from the end (for example, test at the start, go through some drills, and then re-test and compare).

For example, below is an example from a golfer who took 10 swings with driver, and found their strike was fairly inconsistent and tended to include some low and off-center strikes. Their goal was to tighten the dispersion to a location just above the center point to promote a high, low spin launch with driver. They worked on a few things and re-tested at a later time, finding that the dispersion pattern shifted slightly up during the second test.

This can then be accompanied by various statistical methods that quantify the total area covered by the dispersion patterns or the degree of overlap between two different patterns (e.g., pre vs post) if interested in a more formal comparison.

What if you don’t have access to a launch monitor with face impact data?

The data shown so far was gathered using high-end tech like the GC Quad, which has the ability to measure face impact location. This makes the collection and analysis of face impact dispersion patterns fairly convenient.

But what if you don’t have a high-end launch monitor with club-level data? You may not have the convenience and precision offered by that tech, but you can still gather useful feedback on impact location that can move the needle from a practical standpoint.

By either drawing a dot on the back of the ball with a dry erase marker or spraying your club face with various sprays (Dr Scholl’s is a common one), you can receive feedback on where the ball impacted the club face. From there, you can plot out a basic dispersion pattern.

For example, you can make a fairly simple data collection template and just stop to mark the plot every once in a while to build out a dispersion pattern across a session.

You may not have access to a high-end launch monitor, but this is no excuse not to use feedback to your advantage. And importantly, this can be done anywhere with minimal equipment.

But when the tech is available, it can open up a lot of options for how to process, analyze, and utilize that data to drive informed decision-making. More to come on this later.

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