SAT/ACT homeschoolers:
http://www.hslda.org/docs/news/hslda/200105070.asp
Standardized test scores homeschoolers:
http://www.hslda.org/docs/nche/000010/200410250.asp
Yeah I know it is higher than the average of the public school, but less than 100 points higher. The average SAT for public school kids was a 1019.
My public school kid got a 1410 with no prep on the verbal and about an hour of prep for the math - and that was while preparing for All States on her instrument, carrying 5 AP classes, volunteering 10 hours a week at the Free Clinic, and practicing 3 hours a day, 6 days a week for a varsity sports team.