You go baby!!
In addition to the fact that statistical measuring for human beings is a
dubious practice (in that people are not static objects), there are not
enough graduates of Sudbury Schools to form a large enough sample
population from which to make any meaningful statistical assertions. All
there are are case studies (Free At Last, etc.) which have no statistical
value. Of course, I say that polls and studies with sample populations in
the millions are frought with confounding and have very little statistical
value, so consider the source.
In any case, I think that parents who would look at outcome-based studies
to make a determination on how their children are going to spend their
childhood are focused on specific results rather than self-determination
and quality-of-life, are pretty much into controlling their kids, and
possibly are not good candidates for the Sudbury Model (oops, there I go
doing negative PR again <g>).