Case Study 3:

 


Impact of new housing projects in New York state Municipalities.

VARIABLES:

     State  Code
     County  Code
     Expenditure per person
     Wealth per person
     Population
     Percent intergovernmental
     Density
     Mean Income per person
     id #  (for matching)
     Growth rate
 

Dataset : NYM
 

     VARIABLE NAMES:

"ST" "CO" "EXPEN" "WEALTH" "POP"  "PINTERG" "DENS"
"INCOME"  "ID"      "GROWR"

          NY Municipalities data

     TOWNS OF INTEREST:

        ST CO EXPEN WEALTH  POP PINTERG DENS INCOME ID GROWR
WARWICK 36 33   237  78908 16225  24.7  170  19044 8730 30.3
MONROE  36 33   159  55067  9338   8.8  599  16726 5420 30.0
TUXEDO  36 33   926 155034  2328   6.1   52  30610 8400  2.5

   QUESTION : PREDICT EXPENDITURE FOR YEARS 2005 and 2025

     Year  POP WEALTH PINTERG DENS INCOME

     1992 16225   78908  24.7  170 19044
     2005 20442   85000  24.7  214 19500
     2025 31033   89000  26.0  325 20000

     1992  7750   55067   8.8  599 16726
     2005  8996   58000   8.8  695 17100
     2025 12413   60000  10.1  959 18000

     1992  2317  155034   6.1   52 30610
     2005 10685  116000   6.1  249 28300
     2025 29246  115000   7.0  656 25000
 
 

What I expected of you for today is to have a lot of questions and to
show us some basic attempts to fit the data. Writing the report is
something that you should have in mind when you ask the questions.
For example what is it that we need to know....
 

You must follow the format for report writing that was described in last week's notes but you still have plenty of freedom about style and content. The report could be addressed as having a group of questions in mind and answering them. Of course you need an introduction with the basic facts. It should not be too long you do notneed to describe the problem in detail because everybody should know it, but just the fact that are relevant to the analysis.

SAS PROGRAM:

SAS OUTPUT:
 
 
 

Variable=EXPEN
                               Histogram                         #            Boxplot
        3300+*                                                   1               *
            .*                                                   1               *
            .
            .*                                                   1               *
            .*                                                   1               *
            .
            .*                                                   1               *
            .*                                                   2               *
        1700+*                                                   1               *
            .*                                                   2               *
            .*                                                   1               *
            .*                                                   9               *
            .**                                                 11               *
            .****                                               29               0
            .*********                                          80               0
            .***********************************************   421            +--+--+
         100+****************************************          353            +-----+
             ----+----+----+----+----+----+----+----+----+--

     Variable=WEALTH
                               Histogram                         #            Boxplot
      575000+*                                                   2               *
            .
            .*                                                   1               *
            .*                                                   2               *
            .*                                                   2               *
            .*                                                   6               *
            .*                                                   1               *
            .*                                                   6               *
            .**                                                 25               *
            .***                                                33               0
            .*************                                     180            +--0--+
       25000+***********************************************   656            *-----*
             ----+----+----+----+----+----+----+----+----+--

     Variable=POP
                               Histogram                          #           Boxplot
      470000+*                                                    1              *
            .
            .
            .
            .*                                                    1              *
            .
            .
            .
            .
            .*                                                    1              *
            .
            .
            .*                                                    1              *
            .
            .
            .*                                                    1              *
            .*                                                    1              *
            .
            .*                                                    2              *
            .*                                                    2              *
            .*                                                    4              *

            .*                                                    6              *
            .***                                                 37              *
       10000+************************************************   857           +--0--+
             ----+----+----+----+----+----+----+----+----+---
     Variable=PINTER        Histogram                        #             Boxplot
        67.5+*                                                 2                *
            .**                                                6                *
            .**                                                6                0
            .*                                                 3                0
            .**                                                8                0
            .***                                              11                0
            .*****                                            23                |
            .**********                                       48                |
            .********************                             97                |
            .*****************************                   145             +-----+
            .*********************************************   221             *--+--*
            .******************************************      208             +-----+
            .*************************                       123                |
         2.5+***                                              13                |
             ----+----+----+----+----+----+----+----+----+
     Variable=GROWR
                               Histogram                         #            Boxplot
         290+*                                                   1               *
            .
            .
            .
            .
            .*                                                   1               *
            .
            .
            .
            .*                                                   2               *
            .
            .*                                                   2               *
            .**                                                 13               0
            .********                                           93               0
            .***********************************************   563            +--+--+
            .*******************                               225            +-----+
            .**                                                 13               0
         -50+*                                                   1               *
             ----+----+----+----+----+----+----+----+----+--
     Variable=LEX
                              Histogram                       #             Boxplot
           8.1+*                                              2                *
              .*                                              1                *
              .*                                              2                *
              .*                                              3                0
              .*                                              3                0
              .**                                             6                0
              .**                                             7                0
           6.7+***                                           11                0
              .*******                                       25                |
              .*******                                       27                |
              .*************                                 52                |
              .*******************                           73                |
              .**************************                   103             +-----+
              .******************************************   167             *--+--*
           5.3+*****************************************    161             |     |
              .*******************************              124             +-----+
              .*********************                         82                |
              .**********                                    38                |
              .*****                                         17                |
              .**                                             5                0
              .*                                              4                0
           3.9+*                                              1                0
               ----+----+----+----+----+----+----+----+--
     Variable=LW            Histogram                      #             Boxplot
          13.3+*                                             2                *
              .*                                             3                0
              .*                                             1                0
              .**                                            7                0
              .*                                             1                0
              .**                                            6                0
              .*****                                        18                0
              .****                                         15                |
              .****                                         15                |
              .********                                     31                |
              .***********                                  44                |
          11.1+************                                 47                |
              .*******************                          76             +-----+
              .*************************                    99             |     |
              .**********************************          135             *--+--*
              .*****************************************   161             |     |
              .***********************************         138             +-----+
              .*********************                        84                |
              .******                                       23                |
              .**                                            5                |
              .*                                             1                |
              .*                                             1                |
           8.9+*                                             1                0
               ----+----+----+----+----+----+----+----+-

                 Plot of EXPEN*GROWR.  Legend: A = 1 obs, B = 2 obs, etc.
      4000 +
           |
           |
           |
           |
           |                 A
           |
      3000 +                   A
           |
           |
     EXPEN |              A
           |             A
           |
           |
      2000 +                   A
           |            A    A
           |                  A
           |                           A
           |               A   A
           |
           |                  ABB A
      1000 +              A  AB B
           |              A AAADA
           |             AA BDBBCA A
           |            A BAAFEFIDB   A
           |               DHRQQIGCBCA          A
           |              AAIZZZZZVPG AB                        A
           |              BEDZZZZZVNIDCC   AA      A
         0 +        A         B A       A                                          A
           -+--------+--------+--------+--------+--------+--------+--------+--------+
          -100      -50       0       50       100      150      200      250     300

                                              GROWR
                  Plot of EXPEN*POP.  Legend: A = 1 obs, B = 2 obs, etc.
      4000 +
           |
           |
           |
           |
           | A
           |
      3000 + A
           |
           |
     EXPEN | A
           | A
           |
           |
      2000 + A
           | B
           | A
           | A
           | B
           |
           | E A
      1000 + F
           | GB
           | NA A A
           | ZCBBAA     A
           | ZHFBBAA  B               A       A
           | ZZMMIABB   AAA B      A                  A            A           A
           | ZZOCDB  A
         0 + BC A
           --+-------------+-------------+-------------+-------------+-------------+-
             0          100000        200000        300000        400000       500000
                                               POP

                 Plot of LEX*LGROWR.  Legend: A = 1 obs, B = 2 obs, etc.
     LEX |
         |
       9 +
         |
         |
         |
         |
       8 +                   A                    A
         |       A A
         |     A               A                      A
         |                        A                                A
         |          A                                 A
       7 +        A              A           A     B   AA B  A
         |        A          A  A      A      A      AAA A
         |       AA     AA  A  A      A  A       A     A  CA   A
         |     A   A     BA  AAA BBA     A     A ABA  A ACBBB A   A
         |        A BA AA AB A AAA    A AA  A     CB B A BB AAA BA
       6 +         AA ABDACAAA ACBA  A    AA AAAAAAACBAAACBBBBAAAA      A
         |          A   BCCADA CAA    BACAAADAAACBAACCFBCAGDADCBBAA
         |             AAAC CCBE BBBE  A E  AAD CADIEDGFMGMBFHCCBB
         |         B     CCCBAGBBBAAA A ABC ABCEDDBGCJIBGEGCMNBJD AB         A
         |          AA  A BDBDBDDADBCACAADBAAAGBBDAFFBEFJEGHMFCFADBB  A
       5 +        A    A AA    AA AAC AA   A AEBBBDCCICBDBFGCJBDBBAA  A
         |        A A    A  A A AB      A  AABABB AEACEDCBFGCB
         |          A A   A  AA A       AA  A  A A  AB  CBE     A        A
         |                A                  A      B    A   B   A  A
         |                         A                      B        A
       4 +  A                         A                             A           A
         |
         ---+-------------+-------------+-------------+-------------+-------------+--
           -4            -2             0             2             4             6
                  Plot of LEX*LPOP.  Legend: A = 1 obs, B = 2 obs, etc.
     LEX |
         |
       9 +
         |
         |
         |
         |
       8 +       A      A
         |           A      A
         |    A          A          A
         |              A            A
         |         AA
       7 +             A A  A B A  A  B            A
         |              A  A A  B A A A          A
         |            B    B AC   B A      B          A  A
         |            A  CAAB B BDAA CA B       A   BB  AA     A
         |             A  AAAC DB DBBBBA  AA A   AB      AA   A
       6 +               BABADCFEDFAABBB  B ABAA  BA A BA    A
         |           A  B   AABAFIDGEGF ECB ABCA A AA B D BA   A B   A AA
         |                 ABBELFOIIIKIGECDAAAFADBAB  EBAA          A     AA
         |                 B CEAELHQTKHDLDHFGDE   ABCCC C   A   B
         |                   BACAFFJLMJPGJHFKJEDDHABB    AA
       5 +                    AACDFBELHDGHDHBBBDDBAA ABA
         |                   AA  C CADDBHEDCFBDABA AA  A  A A
         |                    AAA B  BBEADBAAAA A
         |                           AACAAA  A
         |                           B    A A
       4 +                        A         B        A
         |
         ---+-------------+-------------+-------------+-------------+-------------+--
            4             6             8            10            12            14
                                             LPOP
                Plot of LEX*LDENS.  Legend: A = 1 obs, B = 2 obs, etc.

     LEX |
         |
       9 +
         |
         |
         |
         |
       8 +  B
         |       B
         |  A         A  A
         |       A                    A
         |       B
       7 +       A  A AB A  A          A         AA
         |       A  B    A   AA     A   A             A
         |          A  A A A BC  A   A           AA AA
         |             A AACBCAACA BCA    A       A  A A  A A  A  A     A
         |               AAC CABAB CCBBAA    A AA    A A    A A A A
       6 +             A  ABCBAEBICECCC  AA B   AA   AAAA  A A A     A
         |                 BACABCBFGJFFBEDC  A B  B A AAABAB A B AC AAA
         |                 A AEDBHOFNJIFHEFEDBAADABBBBB AEAA   A  A  A  A
         |                A A   ADFJSGQQHGIFEEBFAFAABDDA A B B   B   A   A
         |                     AABAFFFKQPPILFGJDECCFBAAB B   C     A
       5 +                        B FFFGHIGKDCFBA CEAAAAAB B
         |                         B BECEBEIDBDECB  C   B    B
         |                        C  AAAAC EDBBA A   A
         |                             A C BA AA
         |                                A B  A
       4 +                            A        A   A                   A
         |
         ---+-------------+-------------+-------------+-------------+-------------+--
            0             2             4             6             8            10
                                             LDENS
     Model: MODEL1
     Dependent Variable: LEX
                                  Parameter Estimates
                            Parameter      Standard    T for H0:
           Variable  DF      Estimate         Error   Parameter=0    Prob > |T|

           INTERCEP   1      9.128891    1.84162410         4.957        0.0001
           LW         1      0.326899    0.02870269        11.389        0.0001
           LPOP       1     -2.269150    0.67760970        -3.349        0.0008
           LPOP2      1      0.243843    0.07875894         3.096        0.0020
           LPOP3      1     -0.008099    0.00296974        -2.727        0.0065
           PINTERG    1     -0.083776    0.01017274        -8.235        0.0001
           PINT2      1      0.002605    0.00037065         7.028        0.0001
           PINT3      1  -0.000023080    0.00000387        -5.971        0.0001
           LDENS      1     -0.181394    0.13947979        -1.301        0.1938
           LDENS2     1     -0.056308    0.03251611        -1.732        0.0837
           LDENS3     1      0.006721    0.00230544         2.915        0.0036
           LINCOME    1      0.155568    0.07218570         2.155        0.0314
           LGROWR     1     -0.015870    0.00658608        -2.410        0.0162
                                      Cook's
              Obs    -2-1-0 1 2            D

              885  |      |****  |     0.034
              886  |      |***   |     0.011
              887  |******|      |     0.677
              888  |      |*     |     0.000
              889  |      |**    |     0.001
              890  |    **|      |     0.000
              891  |     *|      |     0.006
              892  |      |      |     0.000
              893  |    **|      |     0.000
              894  |      |**    |     0.001
              895  |      |*     |     0.000
              896  |     *|      |     0.000
              897  |      |**    |     0.004
              898  |      |      |     0.000
              899                       .
              900  |      |**    |     0.001
              901  |    **|      |     0.001
              902  |      |      |     0.000
              903  |      |      |     0.000
                                   Parameter Estimates

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

           INTERCEP   1      8.364134    1.81187251         4.616        0.0001
           LW         1      0.337906    0.02822854        11.970        0.0001
           LPOP       1     -2.123000    0.66543637        -3.190        0.0015
           LPOP2      1      0.236876    0.07730017         3.064        0.0022
           LPOP3      1     -0.008398    0.00291483        -2.881        0.0041
           PINTERG    1     -0.081084    0.00999342        -8.114        0.0001
           PINT2      1      0.002560    0.00036382         7.035        0.0001
           PINT3      1  -0.000022923    0.00000379        -6.043        0.0001
           LDENS      1     -0.148868    0.13698980        -1.087        0.2775
           LDENS2     1     -0.072503    0.03202610        -2.264        0.0238
           LDENS3     1      0.008932    0.00229281         3.896        0.0001
           LINCOME    1      0.158749    0.07084256         2.241        0.0253
           LGROWR     1     -0.017031    0.00646630        -2.634        0.0086
                                   Analysis of Variance
                                      Sum of         Mean
             Source          DF      Squares       Square      F Value       Prob>F

             Model           12    176.48254     14.70688      123.144       0.0001
             Error          897    107.12709      0.11943
             C Total        909    283.60962

                 Root MSE       0.34558     R-square       0.6223
                 Dep Mean       5.49063     Adj R-sq       0.6172
                 C.V.           6.29407                              Parameter Estimates

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

           INTERCEP   1      8.678552    1.79868778         4.825        0.0001
           LW         1      0.338767    0.02799706        12.100        0.0001
           LPOP       1     -2.355506    0.66252610        -3.555        0.0004
           LPOP2      1      0.267774    0.07705389         3.475        0.0005
           LPOP3      1     -0.009729    0.00291001        -3.343        0.0009
           PINTERG    1     -0.080061    0.00991450        -8.075        0.0001
           PINT2      1      0.002524    0.00036094         6.994        0.0001
           PINT3      1  -0.000022594    0.00000376        -6.004        0.0001
           LDENS      1     -0.050738    0.13806901        -0.367        0.7133
           LDENS2     1     -0.103158    0.03267789        -3.157        0.0016
           LDENS3     1      0.011627    0.00237202         4.902        0.0001
           LINCOME    1      0.175452    0.07038409         2.493        0.0129
           LGROWR     1     -0.016589    0.00641405        -2.586        0.0099

                    Stepwise Procedure for Dependent Variable LEX

     Step 1   Variable LW Entered        R-square = 0.40240739   C(p) =582.99726317

                      DF         Sum of Squares      Mean Square          F   Prob>F

      Regression       1           113.28220824     113.28220824     610.08   0.0001
      Error          906           168.22904622       0.18568327
      Total          907           281.51125446

                      Parameter        Standard          Type II
      Variable         Estimate           Error   Sum of Squares          F   Prob>F

      INTERCEP      -0.49677927      0.24289341       0.77672675       4.18   0.0411
      LW             0.56523742      0.02288424     113.28220824     610.08   0.0001

     Bounds on condition number:            1,            1
     --------------------------------------------------------------------------------

     Step 2   Variable LDENS Entered     R-square = 0.48338211   C(p) =383.50684314

     --------------------------------------------------------------------------------

     Step 3   Variable LDENS3 Entered    R-square = 0.59505421   C(p) =107.63173004
     --------------------------------------------------------------------------------

     Step 4   Variable LGROWR Entered    R-square = 0.60075340   C(p) = 95.45036599
     --------------------------------------------------------------------------------

     Step 7   Variable PINT3 Entered     R-square = 0.63239624   C(p) = 22.71309905

     --------------------------------------------------------------------------------

     Step 8   Variable LINCOME Entered   R-square = 0.63449188   C(p) = 19.49848848

                      DF         Sum of Squares      Mean Square          F   Prob>F

      Regression       8           178.61660425      22.32707553     195.07   0.0001
      Error          899           102.89465021       0.11445456
      Total          907           281.51125446

                      Parameter        Standard          Type II
      Variable         Estimate           Error   Sum of Squares          F   Prob>F

      INTERCEP       2.74449327      0.50441862       3.38824829      29.60   0.0001
      LW             0.33493799      0.02780928      16.60284462     145.06   0.0001
      PINTERG       -0.07904981      0.00973812       7.54196606      65.89   0.0001
      PINT2          0.00252008      0.00035717       5.69795441      49.78   0.0001
      PINT3         -0.00002269      0.00000374       4.21351271      36.81   0.0001
      LDENS         -0.50367595      0.02842944      35.92518565     313.88   0.0001
      LDENS3         0.00499558      0.00034247      24.35386781     212.78   0.0001
      LINCOME        0.15976080      0.07036884       0.58994659       5.15   0.0234
      LGROWR        -0.01742089      0.00637521       0.85464441       7.47   0.0064

     Bounds on condition number:     350.2561,      4610.76
     --------------------------------------------------------------------------------

     All variables left in the model are significant at the 0.1500 level.
     No other variable met the 0.1500 significance level for entry into the model.

              Summary of Stepwise Procedure for Dependent Variable LEX

             Variable        Number   Partial    Model
      Step   Entered Removed     In      R**2     R**2      C(p)          F   Prob>F

         1   LW                   1    0.4024   0.4024  582.9973   610.0830   0.0001
         2   LDENS                2    0.0810   0.4834  383.5068   141.8498   0.0001
         3   LDENS3               3    0.1117   0.5951  107.6317   249.2965   0.0001
         4   LGROWR               4    0.0057   0.6008   95.4504    12.8902   0.0003
         5   PINTERG              5    0.0016   0.6024   93.4558     3.6415   0.0567
         6   PINT2                6    0.0151   0.6174   57.9492    35.4993   0.0001
         7   PINT3                7    0.0150   0.6324   22.7131    36.6371   0.0001
         8   LINCOME              8    0.0021   0.6345   19.4985     5.1544   0.0234
 
 
 

     N = 908     Regression Models for Dependent Variable: LEX
 

      Adjusted  R-square    Variables in Model
      R-square           In

     0.6358478 0.6402642 11 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS2 LDENS3
                            LINCOME LGROWR
     0.6354960 0.6403185 12 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS LDENS2
                            LDENS3 LINCOME LGROWR
     0.6337453 0.6377834 10 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS2 LDENS3
                            LGROWR
     0.6335406 0.6375810 10 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS2 LDENS3
                            LINCOME
     0.6333749 0.6378213 11 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS LDENS2
                            LDENS3 LGROWR
     0.6331814 0.6376302 11 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS LDENS2
                            LDENS3 LINCOME
     0.6318487 0.6363136 11 LW LPOP LPOP2 LPOP3 PINTERG PINT2 PINT3 LDENS LDENS3
                            LINCOME LGROWR
     0.6313896 0.6350473  9 LW PINTERG PINT2 PINT3 LDENS LDENS2 LDENS3 LINCOME LGROWR
     0.6313555 0.6358264 11 LW LPOP LPOP2 PINTERG PINT2 PINT3 LDENS LDENS2 LDENS3
                            LINCOME LGROWR
     0.6312393 0.6344919  8 LW PINTERG PINT2 PINT3 LDENS LDENS3 LINCOME LGROWR
     0.6311713 0.6352377 10 LW LPOP LPOP2 PINTERG PINT2 PINT3 LDENS LDENS3 LINCOME
                            LGROWR
     0.6310451 0.6351129 10 LW LPOP3 PINTERG PINT2 PINT3 LDENS LDENS2 LDENS3 LINCOME
                            LGROWR
     0.6310135 0.6350817 10 LW LPOP2 PINTERG PINT2 PINT3 LDENS LDENS2 LDENS3 LINCOME
                            LGROWR
     0.6309898 0.6354651 11 LW LPOP LPOP3 PINTERG PINT2 PINT3 LDENS LDENS2 LDENS3
                            LINCOME LGROWR

              Backward Elimination Procedure for Dependent Variable LEX

     Step 0    All Variables Entered     R-square = 0.64031851   C(p) = 13.00000000

                      DF         Sum of Squares      Mean Square          F   Prob>F

      Regression      12           180.25686745      15.02140562     132.78   0.0001
      Error          895           101.25438701       0.11313339
      Total          907           281.51125446

                      Parameter        Standard          Type II
      Variable         Estimate           Error   Sum of Squares          F   Prob>F

      INTERCEP       8.67855174      1.79868778       2.63374522      23.28   0.0001
      LW             0.33876721      0.02799706      16.56412705     146.41   0.0001
      LPOP          -2.35550556      0.66252610       1.43005618      12.64   0.0004
      LPOP2          0.26777440      0.07705389       1.36628045      12.08   0.0005
      LPOP3         -0.00972914      0.00291001       1.26458864      11.18   0.0009
      PINTERG       -0.08006091      0.00991450       7.37717980      65.21   0.0001
      PINT2          0.00252434      0.00036094       5.53380577      48.91   0.0001
      PINT3         -0.00002259      0.00000376       4.07790415      36.05   0.0001
      LDENS         -0.05073846      0.13806901       0.01527823       0.14   0.7133
      LDENS2        -0.10315774      0.03267789       1.12742153       9.97   0.0016
      LDENS3         0.01162658      0.00237202       2.71805055      24.03   0.0001
      LINCOME        0.17545199      0.07038409       0.70300507       6.21   0.0129
      LGROWR        -0.01658922      0.00641405       0.75679540       6.69   0.0099

     Bounds on condition number:     17515.01,     345502.9
     --------------------------------------------------------------------------------

     Step 1   Variable LDENS Removed     R-square = 0.64026424   C(p) = 11.13504615

                      DF         Sum of Squares      Mean Square          F   Prob>F

      Regression      11           180.24158922      16.38559902     144.97   0.0001
      Error          896           101.26966524       0.11302418
      Total          907           281.51125446

                      Parameter        Standard          Type II
      Variable         Estimate           Error   Sum of Squares          F   Prob>F

      INTERCEP       9.06958159      1.44948605       4.42504596      39.15   0.0001
      LW             0.34097629      0.02733090      17.59186741     155.65   0.0001
      LPOP          -2.52224957      0.48252866       3.08817037      27.32   0.0001
      LPOP2          0.28686074      0.05689168       2.87353198      25.42   0.0001
      LPOP3         -0.01043163      0.00219300       2.55739800      22.63   0.0001
      PINTERG       -0.08043663      0.00985688       7.52662295      66.59   0.0001
      PINT2          0.00253471      0.00035966       5.61367623      49.67   0.0001
      PINT3         -0.00002268      0.00000375       4.12639603      36.51   0.0001
      LDENS2        -0.11462431      0.00970272      15.77386911     139.56   0.0001
      LDENS3         0.01239009      0.00114392      13.25961238     117.32   0.0001
      LINCOME        0.17482331      0.07032932       0.69838867       6.18   0.0131
      LGROWR        -0.01657313      0.00641080       0.75536390       6.68   0.0099

     Bounds on condition number:     9557.367,     167198.3
     --------------------------------------------------------------------------------

     All variables left in the model are significant at the 0.1000 level.

        Summary of Backward Elimination Procedure for Dependent Variable LEX

              Variable   Number   Partial     Model
      Step    Removed        In      R**2      R**2        C(p)           F   Prob>F

         1    LDENS          11    0.0001    0.6403     11.1350      0.1350   0.7133
 
 
 

     OPTIONS PS=40 lS=80;

     data a;
     infile 'nym';
     input nn ST CO EXPEN WEALTH POP PINTERG DENS INCOME ID GROWR ;
     lex = log(expen);
     lw = log(wealth);
     lpop = log(pop);
     ldens = log(dens);
     lincome = log(income);
     pint2 = pinterg**2;
     pint3 = pinterg**3;
     lpop2 = lpop**2;
     ldens2 = ldens**2;
     lpop3 = lpop**3;
     ldens3 = ldens**3;

     if growr < 0 then lgrowr = - log(-growr);
     if growr > 0 then lgrowr =  log(growr);
     if _N_ ne 887;
     if _N_ ne 475;
     run;
 

     run;

     proc univariate plot;
     var  ST CO EXPEN WEALTH POP PINTERG DENS INCOME ID GROWR
         lex lw lpop ldens lincome;

     proc plot;
     plot  EXPEN*(growr wealth pop dens income PINTERG GROWR);
     plot lex*(lgrowr lw lpop ldens lincome);
     run;

     proc reg;
     model lEX = lW lPOP lpop2 lpop3 PINTERG pint2 pint3 lDENS ldens2 ldens3 lINCOME
                 lGROWR/ P R;
     run;

     proc reg data = a;
     model lEX = lW lPOP lpop2 lpop3 PINTERG pint2 pint3 lDENS ldens2 ldens3 lINCOME
                 lGROWR/ METHOD=stepwise;

     proc reg data = a;
     model lEX = lW lPOP lpop2 lpop3 PINTERG pint2 pint3 lDENS ldens2 ldens3 lINCOME
                 lGROWR/ METHOD=backward;

     proc reg data = a;
     model lEX = lW lPOP lpop2 lpop3 PINTERG pint2 pint3 lDENS ldens2 ldens3 lINCOME
                 lGROWR/ METHOD=adjrsq;

     run;
 

If you use Splus here are some basic comments about modeling.
 
 


     Example:

     lm.ny <- lm(LEXPEN~LPOP+LDENS+LWEALTH+LINCOME+PINTERG+GROWR,data=x.s)
 
 

             summary(lm.ny)  will print coeff's , t-vals,..R^2 ...
             anova(lm.ny) prints the anova table...
 
             plot(lm.ny)
     will produce a plot of residuals vs predicted values
Lets say that high expenditures happen for different reasons and their relation to population and to wealth or income is complicated... It is easier to just look a a part of the data where we have to do the prediction and hope that the complicated relationship has became simpler for that subset.
     ================SOME OUTPUT===========

     # Initial graphs of all the variables.

     postscript("tmp")
     pairs(~.,data=x.s[,c(3:8,10)],pch=".")
     pairs(~.,data=x.s[,c(6,10:15)],pch=".")

     nam <- names(x.s[,c(6,10:15)])

     par(mfrow=c(2,2),pty="s")
     plot( x.s$LINCOME, x.s$LEXPEN,pch=183)

     s1 <-  identify( x.s$LINCOME, x.s$LEXPEN)
     s2 <- unique(s2)
     s2 <-  identify( x.s$LINCOME, x.s$LEXPEN)
     s2 <- unique(s2)

     # Explore the relationship between LINCOME , LWEALTH , LEXPEN, LPOP

     plot( x.s$LINCOME, x.s$LEXPEN,pch=".")
     points( x.s$LINCOME[s1], x.s$LEXPEN[s1], pch="*")
     points( x.s$LINCOME[s2], x.s$LEXPEN[s2], pch="O")

     plot( x.s$LWEALTH, x.s$LEXPEN,pch=".")
     points( x.s$LWEALTH[s1], x.s$LEXPEN[s1], pch="*")
     points( x.s$LWEALTH[s2], x.s$LEXPEN[s2], pch="O")

     plot( x.s$LPOP, x.s$LEXPEN,pch=".")
     points( x.s$LPOP[s1], x.s$LEXPEN[s1], pch="*")
     points( x.s$LPOP[s2], x.s$LEXPEN[s2], pch="O")

     graphics.off()

     #  Fit the basic linear model with lm()

     > lm.ny <- lm(LEXPEN~LPOP+LDENS+LWEALTH+LINCOME+PINTERG+GROWR,data=x.s)

     > summary(lm.ny)
     anova(lm.ny)
 

     Call: lm(formula = LEXPEN ~ LPOP + LDENS + LWEALTH + LINCOME + PINTERG + GROWR, data
              = x.s)
     Residuals:
         Min      1Q  Median    3Q   Max
      -1.579 -0.2359 0.01679 0.246 1.638

     Coefficients:
                     Value Std. Error  t value
     (Intercept)  0.790756  0.5902594   1.3397
            LPOP  0.087591  0.0291388   3.0060
           LDENS -0.192027  0.0283077  -6.7836
         LWEALTH  0.522807  0.0296278  17.6458
         LINCOME -0.071884  0.0824464  -0.8719
         PINTERG -0.001489  0.0014275  -1.0430
           GROWR -0.003827  0.0007794  -4.9103

     Residual standard error: 0.3979 on 907 degrees of freedom
     Multiple R-Squared: 0.494

     Correlation of Coefficients:

             (Intercept)    LPOP   LDENS LWEALTH LINCOME PINTERG
     pp   LPOP -0.1718
       LDENS  0.4463     -0.8266
     LWEALTH  0.2935     -0.1520  0.4362
     LINCOME -0.8885      0.0194 -0.4257 -0.6563
     PINTERG -0.1659      0.0848  0.0821  0.2120 -0.0324
       GROWR -0.1846     -0.1248  0.0119 -0.0305  0.1798 -0.0018

     # Get the analysis of variance table related to this model.

     > anova(lm.ny)

     Analysis of Variance Table

     Response: LEXPEN

     Terms added sequentially (first to last)
                Df Sum of Sq  Mean Sq  F Value     Pr(F)
          LPOP   1   15.8017 15.80170  99.8112 0.0000000
         LDENS   1   25.8957 25.89574 163.5700 0.0000000
       LWEALTH   1   94.4967 94.49675 596.8872 0.0000000
       LINCOME   1    0.0001  0.00008   0.0005 0.9816068
       PINTERG   1    0.1752  0.17524   1.1069 0.2930425
         GROWR   1    3.8171  3.81711  24.1107 0.0000011
     Residuals 907  143.5925  0.15832