We have a dataset of 2000 women of whom 1343 are working. Variable wage represents hourly wages and is

expressed in US dollars. The names of the other variables are self-explanatory. The descriptive statistics are

shown below.

summarize age educ married children wage Variable Obs Mean Std. Dev. Min Max age 2,000 36. 208 8.28656 20 59 education 2,000 13. 084 3. 045912 10 20 married 2,000 . 6705 . 4701492 0 1 children 2,000 1. 6445 1. 398963 0 5 wage 1 , 343 23.69217 6.305374 5.88497 45. 80979heckman wage educ age, select (married children educ age) twostep Heckman selection model -- two-step estimates Number of obs 2,000 (regression model with sample selection) Censored obs 657 Uncensored obs 1,343 Wald chi2 (2) 442. 54 Prob > chi2 0. 0000 wage Coef. Std. Err. Z P> Izl [95% Conf. Interval] wage education . 9825259 . 0538821 18.23 0. 000 . 8769189 1. 088133 age . 2118695 .0220511 9.61 0. 000 . 1686502 . 2550888 _cons . 7340391 1. 248331 0. 59 0. 557 -1. 712645 3. 180723 select married . 4308575 074208 5.81 0. 000 . 2854125 . 5763025 children . 4473249 . 0287417 15.56 0. 000 3909922 . 5036576 education . 0583645 . 0109742 5.32 0. 000 . 0368555 . 0798735 age . 0347211 . 0042293 8.21 0.000 . 0264318 . 0430105 _cons -2. 467365 . 1925635 -12.81 0.000 -2.844782 -2. 089948 mills lambda 4.001615 . 6065388 6.60 0.000 2.812821 5. 19041 rho 0. 67284 sigma 5.9473529