Comparative Effect Sizes (d)
l Adult psychotherapy outcomes              : .68
(Smith, Glass & Miller, 1980)
l Children psychotherapy outcomes         : .71
(Casey & Berman, 1980)
l Classroom intervention - Achievement  : .40
(cited in Hattie, Marsh, Neill, & Richards, 1997)
l Classroom intervention - Affective         : .28
(cited in Hattie, Marsh, Neill, & Richards, 1997)
l Self-concept intervention programs       : .37
(Hattie, J.A., 1992)