version 12.1 use "https://www3.nd.edu/~rwilliam/statafiles/blwh.dta" * I. Pooled (Constrained) Model reg income educ jobexp est store baseline * II. Unconstrained Models: Separate Models for each group reg income educ jobexp if black == 0 est store whitemodel reg income educ jobexp if black == 1 est store blackmodel lrtest (blackmodel whitemodel) baseline * IIIa. Intercepts vary across groups, all other parameters the same reg income educ jobexp i.black est store intonly testparm i.black ftest baseline intonly lrtest baseline intonly * IIIb. Intercepts and some slopes vary across groups, other slopes are the same reg income educ jobexp i.black i.black#c.jobexp est store intjob testparm i.black#c.jobexp ftest intonly intjob lrtest intonly intjob * IIIc. Intercepts and all slopes free to vary across groups (totally unconstrained). reg income educ jobexp i.black i.black#c.educ i.black#c.jobexp est store intedjob testparm i.black#c.educ i.black#c.jobexp ftest intonly intedjob lrtest intonly intedjob testparm i.black i.black#c.educ i.black#c.jobexp ftest baseline intedjob lrtest baseline intedjob