Thursday, 16 February 2017

Skytrak Skills Assessment vs Trackman Combine

Tracking shots is great and provides a wealth of data. However, the Trackman Combine test makes you focus on a target and puts you under pressure. I think it is a brilliant practise aid so the ability to complete something similar on Skytrak was a significant factor for me before I purchased it.

Having completed several Trackman Combine tests and plenty of Skytrak SA (Skills Assessment) I thought it would be interesting to see how they compare.

Trackman presents you with various targets (60, 70, 80, 90, 100, 120, 140, 160, 180, Drive). All targets are based on carry distance and based on proximity to the target you are given a score out of 100. They than map the score to a handicap based on real data collected from people completing the combine test.

Trackman does not show the calculated handicap for an individual shot.

Skytrak SA is similar although the distances are based on Total Distance as opposed to carry. If you are using Premium balls and hit the ball consistently your spin rate will be high enough for the difference to be negligible (the ball will stop dead or spin back slightly on the Skytrak Green). Each shot is assigned a dynamic handicap based on proximity to the target.

Having completed 3 combine tests and numerous SA's it is immediately apparent the SA is way more punishing for my ability. My combine scores have ranged between 70-78 which places my Trackman handicap between 0-4. My SA scores have placed me between 5-13.

I therefore set about comparing proximity to calculated handicap to see what patterns emerge:

Some very clear patterns emerge:

  • Skytrak uses a linear equation to calculate handicap from proximity to target.
  • Trackman uses a quadratic equation to calculate handicap from proximity to target.
  • Skytrak and Trackman roughly agree in the 18-20 handicap range.
  • Below 18 Skytrak becomes increasingly punishing compared to Trackman.
  • Above 20 Skytrak becomes increasingly lenient compared to Trackman.

The following chart compares proximity to handicap at varying distances.
From this it becomes even clearer how punishing Skytrak is to better scores. A male scratch golfer will on average score 72 on trackman. He will score a dynamic handicap of approx 8-9 on Skytrak! Because the handicaps converge in the 18-20 region it seems logical the handicap region between 8 and 20 is compressed on Skytrak compared to Trackman (12 handicap units vs 20). This means a 1 shot improvement between 8-20 equates to a real world improvement >1 shot. It also means attaining a 1 shot improvement <8 Sh Hcap becomes exponentially harder compared to Trackman and thusly real life. The Sh Hcap is still in beta (as of 2.5.4) so in my opinion it seems sensible to adjust the algorithm to take this into account.

Using this data and excel it is possible to ascertain conversion equations between the systems:
Th - Trackman Handicap
Ts - Trackman Score
Sh - Skytrak Handicap

Trackman Handicap from Trackman Score
Th = -0.0052Ts2 - 0.1572Ts + 38.226 (r2=0.9952)

Skytrak Handicap from Trackman Handicap
Sh = 0.0077Th2 + 0.4029Th + 8.5378 (r2=0.995)

Trackman Handicap from Skytrak Handicap
Th = -0.0254Sh2 + 2.5073Sh - 19.453 (r2=0.9932)