Your rating will become more accurate, after you play more games.
Look at the absurd case: Your first game, you beat a 2500 GM (he suffers a disconnection or blunders). Would you expect a rating greater than his?
Of course not, and that's why ratings are based on many games.
hmm ok
And that, my friend, is called Rating Deviation.
http://support.chess.com/Knowledgebase/Article/View/16/0/how-do-ratings-work
lol, i knew i would get this kind of answer. i was previously known as AccelerateChess here but my account got hacked ( i was winning against an FM )
i just wanted to see how many ppl would care to reply. and about my old acc , its hacked so i left it. thanks to all who answered
hmm i think they should simply compare with a strong engine -_- but in my analysis i have sometimes played Rybka #1 moves, so i think there's no sure shot way....
the best would be to make it MANDATORY to install a software that does not allow you to open any other program. People can still use other devices though. let's see how the http://www.fide.com/component/content/article/1-fide-news/7318-fide-online-arena.html prevents cheating.
Till now in Online Chess, i haven't lost a single game and beat a 1048, a 1318 and a 1601. still my rating is 1559 . how come? since i beat a 1601 with no loss, should'nt my rating be more than his ?