Originally posted by kw72ukYou got it right first time: it is because your score is provisional. There is info on this in the Help / FAQ bit of the site. The more games you play, the more stable your rating will become, and once you become provisional, your score will only head downwards when you lose.
I just lost a game and my score went up. Is that just because my score is still provisional or will the same happen when I am not provisional any more?