A. In Empirical Exercise 7.1(f), you estimated several regressions and were asked: "What is a reasonable 95% confidence interval for the effect of smoking on birth weight?" i. In Chapter 8 you learned about nonlinear regressions. Can you think of any nonlinear i. In Chapter 8 you learned about nonlinear regressions. Can you think of any nonlinear regressions that can potentially improve your answer to Empirical Exercise E7.1(f)? After estimating these additional regressions, what is a reasonable 95% confidence interval for the effect of smoking on birth weight?