Michigan.do

1
Michigan.do
2

• . construct new variables
• . gen mistate26
• . michigan dummy
• . gen hikemonthgt33
• . treatment period dummy
• . gen treatmenthikemi

3

• . get means of smoking rates for the 2x2 box
• . sort mi hike
• . by mi hike sum smoked

4

• . by mi hike sum smoked
• --------------------------------------------------
  -----------------------------
• -gt mi 0, hike 0
• Variable Obs Mean Std. Dev.
  Min Max
• -------------------------------------------------
  --------------------
• smoked 26441 .1950002 .3962083
  0 1
• --------------------------------------------------
  -----------------------------
• -gt mi 0, hike 1
• Variable Obs Mean Std. Dev.
  Min Max
• -------------------------------------------------
  --------------------
• smoked 18852 .1827923 .3865064
  0 1
• --------------------------------------------------
  -----------------------------
• -gt mi 1, hike 0
• Variable Obs Mean Std. Dev.
  Min Max
• -------------------------------------------------
  --------------------
• smoked 17790 .1957279 .3967712
  0 1
• --------------------------------------------------
  -----------------------------
• -gt mi 1, hike 1
• Variable Obs Mean Std. Dev.
  Min Max

5
Smoking Rates
6

• . now run the regression
• . reg smoked mi hike treatment
• Source SS df MS
  Number of obs 76026
• -------------------------------------------
  F( 3, 76022) 8.59
• Model 3.95288903 3 1.31762968
  Prob gt F 0.0000
• Residual 11663.5888 76022 .153423862
  R-squared 0.0003
• -------------------------------------------
  Adj R-squared 0.0003
• Total 11667.5417 76025 .153469803
  Root MSE .39169
• --------------------------------------------------
  ----------------------------
• smoked Coef. Std. Err. t
  Pgtt 95 Conf. Interval
• -------------------------------------------------
  ----------------------------
• mi .0007277 .0037982 0.19
  0.848 -.0067168 .0081723
• hike -.0122079 .0037337 -3.27
  0.001 -.019526 -.0048898
• treatment -.0051997 .0058668 -0.89
  0.375 -.0166985 .0062991
• _cons .1950002 .0024088 80.95
  0.000 .1902789 .1997215
• --------------------------------------------------
  ----------------------------

Notice the estimate for treatment is
arithmetically Identical to the number from the
2x2 box
7

• . now control for observed characteristics
• . generate dummy variables to control for race,
  parity, education and age
• . xi i.age i.mrace3 i.meduc6 i.ageg
• . add these variables to the model
• . reg smoked mi hike treatment _I

8

• . reg smoked mi hike treatment _I
• Source SS df MS
  Number of obs 76026
• -------------------------------------------
  F( 15, 76010) 474.06
• Model 998.136229 15 66.5424153
  Prob gt F 0.0000
• Residual 10669.4055 76010 .140368445
  R-squared 0.0855
• -------------------------------------------
  Adj R-squared 0.0854
• Total 11667.5417 76025 .153469803
  Root MSE .37466
• --------------------------------------------------
  ----------------------------
• smoked Coef. Std. Err. t
  Pgtt 95 Conf. Interval
• -------------------------------------------------
  ----------------------------
• mi -.0039841 .0036501 -1.09
  0.275 -.0111382 .00317
• hike -.0030636 .0035745 -0.86
  0.391 -.0100696 .0039424
• treatment -.0051552 .0056122 -0.92
  0.358 -.0161551 .0058447
• _Iageg_2 .105199 .0052283 20.12
  0.000 .0949516 .1154464
• Delete some
  results
• _Imeduc6_6 .0156193 .0145937 1.07
  0.284 -.0129844 .044223
• _cons .1476714 .0092008 16.05
  0.000 .1296378 .165705
• --------------------------------------------------
  ----------------------------

9

• . now control for all time periods and all
  states
• . need to define time and state dummies
• . in the regression, drop the mi and hike
  variables
• . xi i.age i.mrace3 i.meduc6 i.ageg i.state
  i.month
• . reg smoked treatment _I

10

• . reg smoked treatment _I
• Source SS df MS
  Number of obs 76026
• -------------------------------------------
  F( 70, 75955) 102.48
• Model 1006.80931 70 14.3829901
  Prob gt F 0.0000
• Residual 10660.7324 75955 .140355901
  R-squared 0.0863
• -------------------------------------------
  Adj R-squared 0.0854
• Total 11667.5417 76025 .153469803
  Root MSE .37464
• --------------------------------------------------
  ----------------------------
• smoked Coef. Std. Err. t
  Pgtt 95 Conf. Interval
• -------------------------------------------------
  ----------------------------
• treatment -.0053194 .0056134 -0.95
  0.343 -.0163216 .0056828
• _Iageg_2 .1051191 .0052311 20.10
  0.000 .0948663 .115372
• Delete some results
• _Istate_26 -.0046835 .0051651 -0.91
  0.365 -.0148071 .0054402
• _Istate_42 -.0009752 .0045039 -0.22
  0.829 -.0098028 .0078525
• _Imonth_2 .0273311 .0136851 2.00
  0.046 .0005083 .0541538
• Delete some results
• _Imonth_3 .0305209 .014018 2.18
  0.029 .0030457 .0579961
• _Imonth_56 .009216 .0148571 0.62
  0.535 -.0199038 .0383358