name of dataset: fertil3
no of variables: 24
no of observations: 72

+----------+-------------------------------+
| variable | label                         |
+----------+-------------------------------+
| gfr      | births per 1000 women 15-44   |
| pe       | real value pers. exemption, $ |
| year     | 1913 to 1984                  |
| t        | time trend, t=1,...,72        |
| tsq      | t^2                           |
| pe_1     | pe[_n-1]                      |
| pe_2     | pe[_n-2]                      |
| pe_3     | pe[_n-3]                      |
| pe_4     | pe[_n-4]                      |
| pill     | =1 if year >= 1963            |
| ww2      | =1, 1941 to 1945              |
| tcu      | t^3                           |
| cgfr     | change in gfr:  gfr - gfr_1   |
| cpe      | pe - pe_1                     |
| cpe_1    | cpe[_n-1]                     |
| cpe_2    | cpe[_n-2]                     |
| cpe_3    | cpe[_n-3]                     |
| cpe_4    | cpe[_n-4]                     |
| gfr_1    | gfr[_n-1]                     |
| cgfr_1   | cgfr[_n-1]                    |
| cgfr_2   | cgfr[_n-2]                    |
| cgfr_3   | cgfr[_n-3]                    |
| cgfr_4   | cgfr[_n-4]                    |
| gfr_2    | gfr[_n-2]                     |
+----------+-------------------------------+

L.A. Whittington, J. Alm, and H.E. Peters (1990), “Fertility and the
Personal Exemption: Implicit Pronatalist Policy in the United States,”
American Economic Review 80, 545-556. The data are given in the
article.