Here's my first basic overview... I'm sure many of the more active players already know this but there are plenty that do not.
How NTRP works (basic explanation):
There is a table that contains the expected outcome (specific score) for every possible match up of players. If you are a 3.45 and I am a 3.30, you will be expected to win by a certain margin. For example’s sake, we’ll say that expected outcome is 6-3, 6-3. If you do win by that exact score, we will both receive a match rating that is the same as our start rate. Note: Start rates are the prior year’s ‘year-end rating’ or for self-rated players a 0.0. If you win the match 6-4, 6-4, I exceeded the expected result, so even though I lost, my rating for that match will be slightly higher than before (ex: maybe up .03). Your rating would drop the same amount for that match. If you win the match 6-2, 6-2, your rating will improve and mine will drop. These match ratings will be averaged to come up with our year-end rating.
There are hundreds of other variables that can also be considered. The algorithm for doubles is very complex, but basically will do the same thing as explained above, but using the average of the two people on the court to determine what the expected outcome would be.
Any player who participated in Championship levels (i.e. Districts, Sectionals and/or Nationals) becomes a Benchmark rated player. Also, anyone who is dynamically disqualified during the league season would become a benchmark. This does not indicate in any way, the level of the player. The rating calculation starts at the National benchmark level, down to Sectionals, down to Districts, down to the local level. Benchmarks drive the ratings for all other players. If you became a benchmark by advancing to Districts and I played against you during the regular season, that match would be weighted more heavily for me, so it could affect my rating more.
One myth that exists (among many) is that the position has an impact on your rating. This is completely false. It doesn’t matter if you play #1 singles or #3 doubles. It just matters who your opponent is since that will determine how you should do in that specific match. Another source of confusion is the assumption that winning means you will move up and losing means you will move down. If a player won every match by a margin that is less than expected, she could actually move down with an undefeated record. Likewise, a player who loses every match could actually move up if she lost by a closer than expected margin in every match. Often times, players’ ratings are moving small or large amounts, but within the level (not quite across the line to the next level).
The 3.5 level is from 3.01 up to 3.50; 4.0 is from 3.51 up to 4.00 and so on. It is possible for one player to have a terrific season and move up .20, but if she started at 3.24, that will move her up to 3.44 and she’ll still be a 3.5. A different player, who had a much worse season, could have started at 3.48 and moved up to 3.52; so she would be a 4.0 level player. If this part of it were transparent, I believe there would be far fewer complaints because players would be able to see that the system is working very well. Unfortunately, since this type of information could be misused by many players, USTA National still does not provide it.
Hopefully that will help you to understand some of the basics behind how NTRP works. Please let me know if you have any other questions.