Key points are not available for this paper at this time.
Thomas P. Carpenter, Elizabeth Fennema, Penelope L. Peterson, Deborah A. Carey, Teachers' Pedagogical Content Knowledge of Students' Problem Solving in Elementary Arithmetic, Journal for Research in Mathematics Education, Vol. 19, No. 5 (Nov., 1988), pp. 385-401
Carpenter et al. (Tue,) studied this question.