Noob questions about varience and Sharkscope.

[LeadbellyDan]

1) Ive played about 200 $16 turbo SnGs and have a ROI of 21%. How close is this likely to be to my real ROI and how many games does it take before varience starts to calm down?

2) My pokertracker says I have an overall ROI of 23%. Sharkscope says I have an ROI of 9%. Whats up with that. I did play about 30 MTTs with -ROI before I started playing SnGs but surely one oft these figures must be wrong. Is Sharkscope unaccurate?