Use the data in SMOKE.DTA for this question. This data set contains information on smoking behavior and other variables for a random sample of single adults from the United States in a certain year.

2 . reg lincome cigs educ age Source SS df MS Number of obs 807 F (3, 803) 31.55 Model 43.1624383 3 14.3874794 Prob > F 0.0800 Residual 366.2334 803 . 456081444 R-squared 9.1054 Adj R-squared 9.1021 Total 409. 395838 806 .507935283 Root MSE . 67534 lincome Coef. Std. Err. t P>It/ [95% Conf. Interval] cigs . 804283 . 801738 2. 46 0.014 . 9008715 . 0076944 educ .8749085 - 807924 9.45 . 0593543 . 8904628 age . 890828 - 8014223 0.58 8.561 -. 9019638 . 8036197 _cons 8. 681793 . 1279868 67. 83 8. 430565 8.933021 3 . reg cigs cigpric educ age agesq Source SS df MS Number of obs 897 F (4, 802) 9.16 Model 6631.90809 4 1657.97702 Prob > F e.0800 Residual 145121.775 802 180.949844 R-squared 0.0437 Adj R-squared 0.0389 Total 151753.683 806 188. 280903 Root MSE 13. 452 cigs Coef. Std. Err. t p>It| [95% Conf. Interval] cigpric - .0317582 . 1801156 -0.32 0.751 - . 2282778 - 1647614 educ - .4780036 .1619667 -2.90 9.084 -. 7879324 - . 1528748 age .8247938 . 1548111 5.33 0.080 . 5209109 1.128677 agesq - . 0095901 . 0016845 -5. 69 0.080 - . 0128967 - . 0062835 _Cons 1. 535673 6.854681 0. 22 0. 823 -11.91956 14.99091