Nevertheless, even the most conservative of our three
methodological approaches suggests substantial variation in principal effectiveness: a principal in the top 16 percent of the quality distribution will produce annual student gains that are 0.05 standard deviations higher than an average principal for all students in their school.
Thus, while these studies
suggest that there may be different
approaches for preparing teacher leaders to provide support, including lesson planning, to classroom teachers, these findings should be viewed with caution due to
methodological concerns in these studies.