Key points are not available for this paper at this time.
Irving Lazar, Richard Darlington, Harry Murray, Jacqueline Royce, Ann Snipper, Craig T. Ramey, Lasting Effects of Early Education: A Report from the Consortium for Longitudinal Studies, Monographs of the Society for Research in Child Development, Vol. 47, No. 2/3, Lasting Effects of Early Education: A Report from the Consortium for Longitudinal Studies (1982), pp. i+iii+v-vii+ix-xiv+1-151
Lazar et al. (1982) studied this question.