How Historical Rankings are created

Same algorithm used to calculate Current Score on a weekly basis, is also used to calculate all quarterly Current Scores back to year 1993.
Historical scores (Current Scores from the past) are calculated for each quarter and for all fighters that were active at that time.
Quarter is represented by the last day of the 3 month period:
Quarter            End Date           Quarter Calculation Date
2012_2            2012-06-30          2012-07-01
2012_1            2012-03-31          2012-04-01
2011_4            2011-12-31          2012-01-01
2011_3            2011-09-30          2011-10-01
How is Historical calculation performed?
Following steps are executed for each quarter:
  1. Delete all data (fights, events, scores) that has date after Quarter End Date.
  2. Calculate Current Score for all active fighters.
  3. Store all fighters Current Scores and ranking data into history table.
  4. Switch to the next quarter (quarter prior to this) and repeat from step 1.
This is repeated 95 times (from quarter 2017_02 to quarter 1993_4).
In the future, as we have new quarters completed, data for the new quarters will be added to the history table.
There are some fighter related data (like weight category or promotion association) that is changing in time.
That data is recorded for each quarter and then used in the process that generates historical rankings.
As a result of this process, we have for every fighter a historical Current Score number in each quarter where fighter was active.
Having all that historical data allow us to:
-       Create ranking lists for every historical period. Rankings are both P4P and in Category.
-       Create timeline for each fighter that represents how fighter career progressed.
-       Compare two fighters from different time periods.
-       Compare how Promotion organizations were strong in each period.
-       Grade Events from historical perspective.
-       Grade and compare weight categories (overall and inside promotions) from different periods.
Following graph shows Historical Scores for several top fighters that had Current Score over 900.