Here are a few links from the Homeschool Legal Defense Association (HSLDA) that might help explain my perspective:
The Scholastic Achievement and Demographic Characteristics of Home School Students in 1998
Strengths of Their Own-Home Schoolers Across America: Academic Achievement, Family Characteristics, and Longitudinal Traits
The above links are from an advocacy source, so I thought I would also include the Wikipedia article on homeschooling. Wikipedia as we all know is not academically rigorous and is hence useless for citations in serious research, but it does provide a fair introduction to many subjects including this one:
Notably, the Wikipedia article includes the following:
Numerous studies have found that homeschooled students on average outperform their peers on standardized tests. Homeschooling Achievement, a study conducted by National Home Education Research Institute (NHERI), supported the academic integrity of homeschooling. Among the homeschooled students who took the tests, the average homeschooled student outperformed his public school peers by 30 to 37 percentile points across all subjects. The study also indicates that public school performance gaps between minorities and genders were virtually non-existent among the homeschooled students who took the tests.