* Reference: Chapter 13 of * Jeffrey M. Wooldridge, Introductory Econometrics: A Modern Approach, * South-Western College Publishing, 2000. SAMPLE 1 239 READ (SLP75_81.shd) age75 educ75 educ81 gdhlth75 gdhlth81 male & marr75 marr81 slpnap75 slpnap81 totwrk75 totwrk81 & yngkid75 yngkid81 ceduc cgdhlth cmarr cslpnap ctotwrk cyngkid * Summary statistics STAT slpnap75 slpnap81 totwrk75 totwrk81 * Example 13.5 * Differencing across the 2 years. GENR cslpnap=slpnap81-slpnap75 GENR ctotwrk=totwrk81-totwrk75 GENR ceduc=educ81-educ75 GENR cmarr=marr81-marr75 GENR cyngkid=yngkid81-yngkid75 GENR cgdhlth=gdhlth81-gdhlth75 * Apply the First-Differenced Estimator - Equation (13.21), p. 424. OLS cslpnap ctotwrk ceduc cmarr cyngkid cgdhlth * The coefficient on ctotwrk gives the average decrease in the * number of minutes sleeping for an additional minute of work, * holding all other variables fixed. * The next TEST command calculates the impact on sleeping for an * additional hour (60 minutes) of work (bottom of p. 424). TEST 60*ctotwrk * Test the joint significance of all variables except ctotwrk * (top of p. 425). TEST TEST ceduc=0 TEST cmarr=0 TEST cyngkid=0 TEST cgdhlth=0 END STOP