2) Consider the following regression predicting birth weight using the variables listed: (10 points) variable name variable label bwght birth weight, ounces cigs cigs smked per day while preg faminc 1988 family income, $1000s motheduc mother's yrs of educ male =1 if male child Source SS df MS Number of obs = 674 Model 12066.6671 4 3016. 66677 Residual 1 305549. 726 669 456. 726048 Total | 317616.393 673 471 . 941149 bwght | Coef. Std. Err. t P>It| [95% Conf. Interval] cigs -. 4370689 . 1358532 faminc . 0812292 . 050534 motheduc . 3334542 . 3955639 male 4. 538161 1 . 661007 cons 110 .1121 4. 849262 a) Explain carefully what the intercept and each of four slope parameter estimates means, including all relevant units. b) Write the formula for R and calculate it for this regression. Explain what R tells us . c) Write the formula for a 95% confidence interval and calculate it for male only. d) Write the formula for a t-statistic that tests the null hypothesis Ho: 3,=0. Calculate the t-statistics for cigs, faminc, motheduc, and male. Which of these are statistically significant at the 18 level (two-tailed), and how do you know