Since the left hand side is birth weight in pounds, it follows that each new coefficient
will be the corresponding old coefficient divided by 16. To verify this, the regression of bwghtlbs on cigs, and faminc is reported in column (2) of Table 6.1. Up to four digits,the intercept and slopes in column (2) are just those in column (1) divided by 16. For example, the coefficient on cigs is now .0289; this means that if cigs were higher by five, birth weight would be .0289(5) .1445 pounds lower. In terms of ounces, we have.1445(16) 2.312, which is slightly different from the 2.32 we obtained earlier due to rounding error. The point is, once the effects are transformed into the same units, we get exactly the same answer, regardless of how the dependent variable is measured.What about statistical significance? As we expect, changing the dependent variable from ounces to pounds has no effect on how statistically important the independent variables are. The standard errors in column (2) are 16 times smaller than those in column(1). A few quick calculations show that the t statistics in column (2) are indeed identical to the t statistics in column (2). The endpoints for the confidence intervals in column (2) are just the endpoints in column (1) divided by 16. This is because the CIs change by the same factor as the standard errors. [Remember that the 95% CI here is