RonFezBuddy said:

The traditional answer to sample size is that it's almost impossible to get to a sample size that is your true ROI.  However, once you get to about 2k I think your results start to become fairly representative.  However, at that point the problem becomes that your skills are probably evolving to where 2000th tourney you play is probably way different than the way you played the 1st of that sample.

 

So, once again there's no small number you can point to and say it's truly indicative but once you get in the multi-thousand I think you can get some more confidence.

 

A small % of players are going to have a winning ROI so anything positive is good.  If you look up the best players they tend to normalize around 15% -45% at the HSMTT level, barring the random giant score.  I think 30% – 55% is pretty good for midstakes.

 

I have no math to back this up.  Just talking to a lot of players over the years.

This is great advice.  Like RFB said it's difficult because you should be playing much better in tourneys 1001-2000 so it's difficult to know your actual ROI I'd say you can get a better idea just like RFB said after about 2k tournaments.