World Ranking Rules and System updated part 2

In January 2021 several changes were implemented in the IOF World Ranking System (WRS). These were:

  • Prolongation of ‘Counting months’ due to COVID-19 restrictions (decided at Council meeting 204)
  • A follow-up to the August 5, 2020 IOF news item about allocation of rankings points
  • Rule changes (New version published)
  • Fixed issues with Ranking algoritm on 4 events.

Prolongation of ‘Counting months’ due to COVID-19 restrictions (Decided on Council meeting 204)

In June 2020, the IOF Council decided to prolong the period(s) back in time, starting from 2020-04-01 during which the athletes’ best results are counted to make up their world ranking points total. Council also decided (in June) that they would revisit the decision in January  2021 if there were still effects of COVID-19 that would affect an athletes’ ability to gain world ranking points. At Council meeting 204 on January 15, it was decided to further prolong the counting periods for FootO, SkiO and MTBO until 30 June 2021. This means that the ‘older’ events (that normally would not count) will still contribute to an athlete’s world ranking points score and make up for lost events during COVID-19 affected periods during 2020 and 2021. A table that visually describes the prolongation can be found here .

A follow-up to the Augsut 5, 2020 IOF news item about allocation of rankings points

The IOF news item of last August described a correction which was made to the code which drives the calculation of rankings points. This then had a major effect on points awarded at WREs in three disciplines, FootO (both Sprint and Forest), MTBO and SkiO. TrailO has a completely different system and was unaffected.

Since then some anomalies which affected a small number of events have been brought to the attention of the Foot-O Commission (FOC). A further analysis of rankings data by the FootO Commission, together with investigations carried out by World Ranking System Developer Tarmo Klaar, discovered two sources of potential anomalies. These were:

  • A clash between date formats used by Eventor and by the World Rankings Scheme which meant that, sometimes, not all a runner’s previous points were recognised as counting towards their previous average. The latter is a key parameter in the points calculation. This bug had an insignificant effect on most calculations but occasionally a significant effect, where participant numbers were low. It has now been fixed.
  • The formula for calculating points is statistically sound where there are many runners but is less appropriate when participant numbers are small. So, a corrective formula has been in use for some time now to deal with such cases. However, the formula has not given results consistent with performance expectations. So to improve the integrity of the system a revised formula was proposed, tested and approved by the IOF Council in December.

Because of the large number of competitions affected by these updates (even though the effects were mostly small), it was decided to backdate them to the beginning of 2018 and recalculate the points awarded at every event which has taken place since then.

The rankings published at the start of January 2021 reflect these changes – some runners may see significant points changes from past WREs as a result. But note that points gained from Major Events will be little affected because of the scaling system which is applied.

Rule Changes

The follow-up mentioned above gave birth to rule changes to better handle lower number of participants and also includes a change where the WR-system is rebased before each calculation instead of annually.


  • 7.4, 7.5 The formula used if there is at least one but fewer than 8 ranked athletes amended to RP = (2000 – RT x (2000 – MP) / MT)
  • 7.5 The formula used if there are no non-outlier ranked athletes amended to formula RP = (2000 – RT x 1200/MT) x IP where MT is the winner’s time
  • Redundant rule 9.4 deleted and subsequent rule renumbered
  • 7.2 Extra item added to define the period over which the average unweighted points is calculated
  • 7.7 Rebasing to be carried out before each calculation rather than annually.

The new version of the rules “World Ranking Scheme Rules 2021 January” can be found in the Competition Rules Section under each Discipline on

Link (To FootO rules)

Fixed issues with Ranking algoritm on 4 events

At the beginning of January, the IOF was informed of an issue with the World Rankings algorithm regarding one specific event. The investigation which followed this discovered that 4 events had points calculated as if the winners score were capped at 1400 when there should have been a maximum score of 1375 instead. This was caused by an input error linked to the change in WRS Rules in Jan 2019 when the maximum score was reduced from 1400 to 1375. The affected events spanned from 2019-01-13 to 2020-06-27 and all have now had points recalculated with the right algorithm. The affected events (IOF Eventor IDs and WRS IDs) were: “6160”, “6199”, “6397” and “6398”.

The IOF would like to apologise to those seeing significant drops in their rankings positions. However, owing to the measures taken as described above, we believe that the World Ranking System is now robust, up to date and adjusted to be a much fairer measure of athletes’ performances. The IOF would also address a special thanks to David May (FOC) and Tarmo Klaar (Developer) for the thorough investigations and also to the Orienteers that have reported anomalies.

If you find any anomalies or have questions, please contact

You can read more about these changes on: Link to more info about WRS and changes (WRS About page)

David Wästlund (System Manager)