THE SAS CODE USED:

data temp;
input zip income lottery black pop;

label
     zip  = 'zip code'
     income = '1997 median household income'
     lottery = '1997 lottery sales (millions)'
     black = 'percent Black'
     pop   = 'total pop'
;

cards;
20019 29230 21.3 98.6 59402
20018 34612 13.5 95.7 18174
20032 26688 11.2 95.6 39928
20020 30980 17.4 95.4 54429
20001 23621 15.5 88.4 34683
20011 40368 18.9 88.2 63092
20002 36477 26.4 82.3 56843
20012 57877 6.8 78.9 15033
20017 46743 4.8 70.9 19584
20010 31924 8.5 63.4 29043
20024 41967 8.6 60.7 11592
20003 50348 9.2 58.3 24889
20005 34240 7.6 48.1 9932
20009 38242 9 45.6 46845
20015 84519 0.8 8.0 14497
20037 48695 2.2 6.5 11109
20016 69206 4.1 5.6 31099
20036 43175 3.5 5.4 4074
20006 32414 4.1 5.1 2308
20008 59636 1.5 5.0 26557
20007 61105 2.7 4.6 27184
;


proc reg;
model lottery = black /stb;
weight pop;
title 'black, with pop weight';

proc reg;
model lottery = income /stb;
weight pop;
title 'income, with pop weight';

proc reg;
model lottery = black income /stb;
weight pop;
title 'black and income with pop weight';

run;

OUTPUT:

BLACK, WITH POP WEIGHT

Model: MODEL1
Dependent Variable: LOTTERY    1997 lottery sales (millions)

                                      Analysis of Variance

                                         Sum of         Mean
                Source          DF      Squares       Square      F Value       Prob>F

                Model            1 21771119.307 21771119.307       31.621       0.0001
                Error           19 13081376.946 688493.52347
                C Total         20 34852496.253

                    Root MSE     829.75510     R-square       0.6247
                    Dep Mean      12.83514     Adj R-sq       0.6049
                    C.V.        6464.71156

                                       Parameter Estimates

                        Parameter      Standard    T for H0:                 Standardized
       Variable  DF      Estimate         Error   Parameter=0    Prob > |T|      Estimate

       INTERCEP   1      0.975225    2.36539722         0.412        0.6847    0.00000000
       BLACK      1      0.179092    0.03184823         5.623        0.0001    0.79035724

                     Variable
       Variable  DF     Label

       INTERCEP   1  Intercept
       BLACK      1  percent Black


INCOME, WITH POP WEIGHT

Model: MODEL1
Dependent Variable: LOTTERY    1997 lottery sales (millions)

                                      Analysis of Variance

                                         Sum of         Mean
                Source          DF      Squares       Square      F Value       Prob>F

                Model            1 14577908.614 14577908.614       13.661       0.0015
                Error           19 20274587.639   1067083.56
                C Total         20 34852496.253

                    Root MSE    1032.99737     R-square       0.4183
                    Dep Mean      12.83514     Adj R-sq       0.3877
                    C.V.        8048.19402

                                       Parameter Estimates

                        Parameter      Standard    T for H0:                 Standardized
       Variable  DF      Estimate         Error   Parameter=0    Prob > |T|      Estimate

       INTERCEP   1     27.221775    4.11435264         6.616        0.0001    0.00000000
       INCOME     1     -0.000352    0.00009516        -3.696        0.0015   -0.64674141

                     Variable
       Variable  DF     Label

       INTERCEP   1  Intercept
       INCOME     1  1997 median household income

BLACK AND INCOME WITH POP WEIGHT

Model: MODEL1
Dependent Variable: LOTTERY    1997 lottery sales (millions)

                                      Analysis of Variance

                                         Sum of         Mean
                Source          DF      Squares       Square      F Value       Prob>F

                Model            2  21775814.62  10887907.31       14.987       0.0001
                Error           18 13076681.633 726482.31295
                C Total         20 34852496.253

                    Root MSE     852.33932     R-square       0.6248
                    Dep Mean      12.83514     Adj R-sq       0.5831
                    C.V.        6640.66765

                                       Parameter Estimates

                        Parameter      Standard    T for H0:                 Standardized
       Variable  DF      Estimate         Error   Parameter=0    Prob > |T|      Estimate

       INTERCEP   1      1.655450    8.80318502         0.188        0.8529    0.00000000
       BLACK      1      0.175463    0.05574371         3.148        0.0056    0.77434426
       INCOME     1  -0.000010755    0.00013378        -0.080        0.9368   -0.01977713

                     Variable
       Variable  DF     Label

       INTERCEP   1  Intercept
       BLACK      1  percent Black
       INCOME     1  1997 median household income

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