Ranking System Flaws

NASGA Ranking System’s Flaws

The ranking points for an event in NASGA Database is the athlete’s best throw / Pro North American Record * 1000.  (the throw expressed as a % of the record times 10).  Thus, in this ranking system, a throw that ties the Pro North American Record receives 1000 points (100% of the record x 10).

This ranking methodology works fine in other divisions when that division’s records are all the same proportion of the North American Pro records, such as the amateur A, B, and C classes.  However, for Lightweight’s and womens’ division, this is not true in several events. For women, the hammer records are considerably less than NASGA’s base line of the North American Pro records and for the lightweights, the LWFD record is much different than NASGA’s base line.

In these events for these divisions, a bias is introduced as the ranking underweights the events that have shorter distances and over weights events with longer distances (such as women’s HWFD).

Example: One thrower ties the LWFD Lightweight record and another ties that divisions HWFD record. 

  • The Lightweight Division’s LWFD record is 75′ and the Pro North American record is 93.042′
    • The Lightweight athlete who tied his division’s LWFD record receives 75/93.042*1000 = 806.09 points in the lightweight (and amateur) rankings for his effort. 
    • Because the Lightweight Division’s LWFD record is considerably less (18.402′) than the Pro North American record, he receives 806.09 points for his efforts in tying the world record for his division. Ideally, this amount should be 1000 points.
    • The difference from 1000 for the LWFD event is 193.91 points and is the bias built into NASGA’s ranking system.   193.31 = (Pro American Record – Lightweight Record)/Pro American Record *1000 = 18.402/ 93.042*1000.
  • The Lightweight Division’s HWFD record is 48.667′ and the Pro North American record is 9.667′

    • The other Lightweight athlete who tied his division’s HWFD record receives 48.667/49.667*1000 = 979.87 points in the lightweight (and amateur) rankings for his effort.
    • The same World record setting effort in the HWFD event yields this lightweight athlete 979.87 point; much closer to the 1000 points representing a record.
    • The difference from 1000 for the HWFD event is 20.13 points and is the bias built into NASGA’s ranking system.   20.13 = (Pro American Record – Lightweight Record)/Pro American Record *1000 = 1.000/49.667 *1000.

This example highlights the bias in ranking when the the Pro American Records are different than the Division Records. Using the Pro North American records do not generate a bias if the division being ranked has a records that are all the same proportion to the North American Pro records. However, this is not the case for Women and Lightweights.

In individual Divisions, this would not be a problem if the record in each event were all the same percentage of the Pro North American records.  However, this is not the case as the below table shows.

bias

For the Women’s Division, NASGA ranking severely under values the hammer events.  When a Women ties either of the World Records, she is awarded just under 800 points in the NASGA ranking system.  However, if she tires the LWFD record, she receives just under 980 points.  But if she ties the HWFD record, she receives 1070 points.  World record setting effort in an unbaised ranking system should receive the same contribution to the rank of the thrower, no matter the event. 

The solution for an unbiased ranking is to use women records for women rankings and Lightweight records for Lightweight Rankings.

NOTE: The Highland Games community is very lucky to have the NASGA website and its database.  I put this page up not to criticize NASGA but to point out the flaws in the ranking system for those who may use it to select throwers for Championships events and those who think beating some one in the database is the same as beating someone on the field. 

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