“Effective schools” is a nebulous term. We could define schools in which students earn top scores on standardized tests as effective; likewise, we could define schools in which students write cogent essays (or create paintings, music, and dance) expounding the evils of standardized tests as effective.
@garyackerman I think history is the judge of effectiveness. We can't know for a few hundred years, except in general terms, if an education was effective. And even then, standards change.