Impact of JLP Removal on Game Outcome


Jammer Lap Points don’t really matter to the outcome of modern Flat-Track Roller Derby.

Disclaimer: This article was written as an individual, with no direct influence or direction from any roller derby association. The views and opinions contained are of the author’s only.


I’m Ref In Peace, most people know me as RIP. I’ve been at this for 11 years now.

An article written calling for the removal of WFTDA Roller Derby’s Jammer Lap Points (JLP) and the accuracy, or lack thereof, in tracking these consistently - by skaters, officials, and fans - has driven a fair amount of discussion on whether these are good, bad, or ugly. The linked article explains a bit on what JLPs are - please review that first for background.

I posit that if we remove the JLP, the outcome of games remain the same - another way to state this is that without JLPs, the team that won with JLPs would also win without JLPs.
This would remove a fair amount of complexity involved with the rules, the application of said rules inconsistently, and the communication of the rules to skaters, officials, and fans.

Note: I have not tried to re-project how JLP scoring changes may have affected rankings, as that’s a study someone else can do at some other time.


In order to perform a modification to remove JLPs, here is the magic formula:

For every scoring pass that has a value of 5, change it to 4. Reevaluate the game outcomes.

At this point, you might protest: Not every Jammer Lap Point results in a 5-point scoring pass!
And you'd be correct.
However, since the resolution of data captured does not have JLPs indicated as anything other than a scored point, and officials don't even track that level of detail during a game, I figured let's start with this and see what the results show.
Also, any non-5-point JLP scoring passes are likely randomly distributed across all teams and games, so the impact of them is going to unlikely to help decide whether JLPs make a difference one way or another.


The WFTDA Stats Repo has a fair amount of data, as recorded and reported by either Rinxter software employed at a game, or by entering all the details to the WFTDA Stats Workbook and then uploaded to the repository. We can leverage this data to try and determine whether removing JLPs has a meaningful change in game outcome.

For simplicity’s sake, I’m going to focus on the data from the 2016 and 2017 seasons (394 games in total) - as they have the bulk of the games played under the rules change from Dec 2014 when the conditions for JLP changed, and a full season of skating and re-training had already elapsed.
There’s no reason the same study couldn’t apply to other time frames - I’m starting with these.

The games recorded span tournaments from home season, regional multi-game events, to playoffs and championships:

  • The Big O 2016
  • BrewHaHa 2016
  • ECDX 2016
  • Uffda Palooza 2016
  • WFTDA D2 Playoffs Wichita
  • WFTDA D2 Playoffs Lansing
  • WFTDA D1 Playoffs Montréal
  • WFTDA D1 Playoffs Columbia
  • WFTDA D1 Playoffs Vancouver
  • WFTDA D1 Playoffs Madison
  • Lone Star Showdown
  • WFTDA Championships Portland
  • BCB 2017 Home Season
  • The Big O 2017
  • BrewHaHa 2017
  • ECDX 2017
  • UffDaPalooza 2017
  • WFTDA D2 Pittsburgh