QUARTERLY JOURNAL OF ECONOMICS
on parental care is likely to be largest on these families with young children who are not likely to be in school. The last speci-
cation of Table V examines whether women learn about tax
changes with a delay after they are implemented. This specica- tion includes both the contemporaneous and one year lagged tax variables. The results are somewhat supportive of a lagged effect of taxes. In the ORG data the contemporaneous tax variable is small and insignicant, while the lagged variable is large and signicant. In the March CPS, it is the contemporaneous variable that is large and signicant, while the lagged variable is smaller and signicant, although still substantial in size.
I. Additional Specications and Hours Worked
We examine several other specications that are not reported here in order to determine the benets of studying many pro- grams at the same time, to check the sensitivity of our results to alternative specications, and to see whether there are particu- larly large effects for certain subgroups of the population. We nd that ignoring some of the policy changes that we study has a substantial effect on the estimates for the remaining programs. When we include the tax variable, but leave out the other policy variables, its coefcient is about 50 percent larger in both sam- ples. When the only policy variables that we include are Medicaid if Work and the Welfare Maximum Benet, the Medicaid coef- cient is positive and signicant in the March CPS sample. When the other policy variables are not included, the waiver variables are much larger. On the other hand, the tax coefcient is hardly changed when the training and child care variables are excluded. These results suggest that the common research strategy of in- vestigating one program in isolation has the potential to give misleading results.
We have examined the sensitivity of our results to alterna- tive samples and variable denitions. In particular, the results are little changed by using more stringent denitions of employ- ment, by including separated women or women in school. We also try several subgroup analyses. In particular, we examine differ- ences between whites and nonwhites, and family heads and sub- family heads. Nonwhites appear to be more affected by welfare waivers than whites, while subfamily heads are more sensitive to taxes than family heads.
To obtain a broader picture of the effects of welfare and tax policy on labor supply, we also examined hours worked (see