Thursday, March 25, 2010
Class-size effects in PISA : further results
Posted by Kevin Denny
Further to my recent post, I show a somewhat detailed analysis above. The dependent variable is the students reading score which is an arbitrary function of class-size (i.e. in their English class, since this is data for Ireland) and of the teacher/pupil ratio in the school. In addition, I control linearly for the students sex, their age in months (they are all about 15), their birth order, their fathers education, school type (private/public) and a few measures of the home environment (like number of books). These controls don't actually make much difference.
So again we see a positive gradient with students in bigger classes doing better though it seems flatter than previously shown. The teacher/pupil ratio doesn't matter: using the absolute number of pupils gives the same result i.e. there are no economies or diseconomies of scale. Repeating the analysis for the maths score gives much the same results. The positive gradient is a puzzle though this is not the first time it has been found.