When you play in competitive Scrabble, you'll know more about ratings and maybe get your own. Rating is a measurement of the performance of a player. If a player has a high rating, he/she is probably a good player. Usually a player who plays in national-scaled tournaments will get national rating and a player who plays in international tournaments will get his/her own international rating from WESPA. Of course the tournaments must be rated to get the ratings. National rating and international rating of one player are not exactly the same.
Some tournaments apply division or section system. This system is divided by ratings. Players with higher rating play in higher division, while players with lower or no rating play in lower/open division. This brings extra competitiveness into the tournaments.
Player's rating under 50 rated games is still considered as provisional rating means that his/her rating is still unstable and not valid enough. WESPA's new rating formula decreases the minimum games to 30 games. After a player passes the minimum games mark, his/her rating will be stabler and truly depict his/her performance. Some players may be overrated or underrated, this could happen in tournaments depends on the opponents they face, also the number of rated players in tournaments.
If a player who has higher rating playing in a tournament which is joined mostly by players with average rating, he/she could probably lose some of his/her rating points if he/she don't play well. Even a player could lose his/her rating although this player finishes top.This also applies to players who have lower rating. Low-rated player could easily get rating points from players with higher rating, should this low-rated player win against players with higher rating.
Here is a link from Scrabble Australia on how rating changes :
http://scrabble.org.au/ratings/system.htm
Example : You are rated 1453. You win 5 out of 7 games against opponents whose average rating is 1393.
1. You are 60 points higher on average.
2. Your probability of winning a game is on average = 50 + 1/12 of 60 = 55%
3. You would be expected to win 55% of the 7 games, ie 3.85 games.
4. You actually won 5 games, which is +1.15 games better than expected.
5. A multiplier of 20 usually applies. Your rating gain is 1.15 x 20 = 23 points.
To wrap things up, rating isn't everything but only as a measurement. It's also not completely valid if you only play one or two tournaments. Losing some isn't the end of the world and gaining some isn't the end of the road :)
ISF Ratings :
http://indonesianscrabble.org/ratings/ranking
WESPA Ratings :
http://www.wespa.org/aardvark/cgi-bin/rating.cgi
