Simultaneous equations analysis of fertility in the U.S.: a comment.

Comments on a study by Conger and Campbell which postulated a 6 equation dynamic model including a fertility equation, estimated by 2 stage least squares on the basis of aggregate data for the U.S. The authors present a table with 3 sets of estimates for each of the 6 structural equations specified in the earlier study; 2 stage least squares estimates obtained for 1946-70 and 1946-76 and the estimates obtained by Conger and Campbell are indicated. The authors report that they were unable to obtain the results reported by the latter; their estimates were quite different and did not seem to support the conclusions offered in the earlier study. Estimates for the longer period were substantially different from those for the shorter. The authors believe that the Conger Campbell data also do not support the Conger-Campbell conclusions. Each point is discussed, with reference to the table. The equations are used to evaluate fertility, female participation, infant mortality, income, education, and medical expenditure.