* R. Carter Hill, William E. Griffiths and Guay C. Lim, * Principles of Econometrics, Third Edition, Wiley, 2008. * Chapter 16.7.5 Tobit estimation of a labour supply function SAMPLE 1 753 READ (mroz.shd) taxableinc federaltax hsiblings hfathereduc hmothereduc & siblings lfp hours kidsl6 kids618 age educ wage wage76 & hhours hage heduc hwage faminc mtr mothereduc fathereduc & unenployment largecity exper * Model Estimation - Table 16.8, page 447. * Least squares estimation OLS hours educ exper age kidsl6 * Least squares, hours > 0 SET NOWARNSKIP SKIPIF (hours.le.0) OLS hours educ exper age kidsl6 DELETE SKIP$ * Tobit estimation TOBIT hours educ exper age kidsl6 / COEF=b * Recover standard errors of the REGRESSION COEFFICIENTS TEST educ/hours TEST exper/hours TEST age/hours TEST kidsl6/hours TEST constant/hours GEN1 sigma=SQRT($sig2) * The saved coefficients in b are the NORMALIZED COEFFICIENTS * The final saved coefficient is 1/sigma PRINT b * Estimate a marginal effect on observed hours of work of an * extra year of education assuming one child at home and other * variables measured at sample means (p. 447). * Save sample means in the variable xm. GENR one=1 STAT educ exper age kidsl6 one hours / MEANS=xm * One child at home. GEN1 xm:4=1 * The final coefficient is not needed GEN1 xm:6=0 MATRIX xb=xm'b GEN1 scale=NCDF(xb) GEN1 meffect=(b:1*sigma)*scale PRINT sigma scale meffect STOP