Can professional development of teachers reduce disparity in student achievement?

This paper describes a national, school-based professional development intervention in which large student achievement gains were previously signaled using single-level regression analyses and effect sizes. However, such analyses can be misleading since educational data typically do not meet independence assumptions. The current study investigates the effectiveness of the professional development intervention using hierarchical linear modelling, with particular focus on whether disparities were reduced for groups typically under-served by the New Zealand education system. Results indicated that students from all learner groups made large gains, especially in writing, but additional targeting would be required to improve equity across student groupings.