* * Dougherty, Introduction to Econometrics, 4th ed * Example from Section 6.4 * Proxy variables * open data eaef21c.xls data(format=xls,org=columns) 1 540 id female male ethblack ethhisp ethwhite age s educprof educphd educmast $ educba educaa educhsd educdo single married divorced faithn faithp faithc faithj faitho asvab01 asvab02 $ asvab03 asvab04 asvab05 asvab06 asvabc height weight85 weight02 sm sf siblings library pov78 earnings $ hours tenure exper collbarg catgov catpri catse urban regne regnc regw regs * linreg s # constant asvabc * linreg s # constant asvabc sm sf library siblings * cmom(corr,print) # asvabc sm sf library siblings