Question about MTT ROI versus 1 table ROI (Mark Blade)

[nath]

Here's a question: how many tournaments played is considered a staistically significant sample size?
Since I became a winning player, I've been pulling a great ROI (I don't have stats before then), but I still don't know how much of it is just being on the good side of variance. (I'm getting close to 200 MTTs if my numbers are correct.)