Since the mean score for a sample composed of several subgroups can be viewed as the sum of the mean of each subgroup weighted by the proportional size of the subgroup, then the mean change in a time period--in this case, from 1972 to 1980--is the sum of the differences between the means for each subgroup, with each mean weighted by its…

Various models of school effects on student achievement were applied in a study of reading and mathematics achievement in the 94 schools of the Oklahoma City Public Schools. The Leadership/Climate Inventory, completed by 1294 teachers, rated school principals in the areas of expectations, instructional leadership, forceful or dynamic style,…