Key points are not available for this paper at this time.
Dan D. Goldhaber, Dominic J. Brewer, Why Don't Schools and Teachers Seem to Matter? Assessing the Impact of Unobservables on Educational Productivity, The Journal of Human Resources, Vol. 32, No. 3 (Summer, 1997), pp. 505-523
Goldhaber et al. (Wed,) studied this question.