where bwght is child birth weight, in ounces, cigs is number of cigarettes smoked by
the mother while pregnant, per day, and faminc is annual family income, in thousands
of dollars. The estimates of this equation, obtained using the data in BWGHT.RAW, are
given in the first column of Table 6.1. Standard errors are listed in parentheses. The estimate on cigs says that if a woman smoked 5 more cigarettes per day, birth weight is
predicted to be about .4634(5) 2.317 ounces less. The t statistic on cigs is 5.03, so the variable is very statistically significant. Now, suppose that we decide to measure birth weight in pounds, rather than in ounces. Let bwghtlbs bwght/16 be birth weight in pounds. What happens to our OLS statistics if we use this as the dependent variable in our equation? It is easy to find the effect on the coefficient estimates by simple manipulation of equation (6.1). Divide this entire equation by 16