however because the distribution of principal characteristics has important equity dimensions such as gender and ethnicity this consideration remains important to any study of educational leadership this question was an important one for talis and remains so for talis especially given evidence of the differential distribution of highly qualified principals across schools boyd et al this challenge is likely to make it harder to develop effective leadership at the school level what appears to matter more though in terms of school improvement and student outcomes is what principals actually do muijs particularly with regard to exercising instructional leadership