----------------------------------------------------------------------------------------------------------------
       log:  C:\EC471\ch4.log
  log type:  text
 opened on:  11 Dec 2003, 21:15:16

. set more 1;

. ***********************************;
. *** Modify the next line so that the path is correct for your data;
. use caschool.dta;

. *;
. *;
. * Decription of Data;
. * dist_code -- district Code;
. * Read_scr  -- avg Reading Score;
. * Math_scr  -- avg Math Score;
. * County   --  county;
. * District -- District;
. * gr_span -- grade span of district;
. * enrl_tot -- total enrollment;
. * teachers -- number of teachers;
. * computer -- number of computers;
. * testscr -- avg test score (= (read_scr+math_scr)/2 );
. * comp_stu -- computers per student ( = computer/enrl_tot);
. * expn_stu -- expentitures per student;
. * str -- student teacher ration (teachers/enrl_tot);
. * el_pct -- percent of English Learners;
. * Meal_pct -- Percent qualifying for reduced-price lunch;
. * clw_pct -- Percent qualifying for CalWorks;
. * aving -- district average income (in $1000's);
. **************************************************************;
. ***** Table 4.1 ******
> **************************************************************;
. summarize str str;

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
         str |       420    19.64043    1.891812         14       25.8
         str |       420    19.64043    1.891812         14       25.8

. pctile pct_tsc = testscr, nq(20) genp(pctx);

. pctile pct_str = str, nq(20);

. list pctx pct_str pct_tsc in 1/20;

     +---------------------------+
     | pctx    pct_str   pct_tsc |
     |---------------------------|
  1. |    5   16.41658    623.15 |
  2. |   10   17.34573   630.375 |
  3. |   15   17.74146     634.1 |
  4. |   20    18.1497   636.975 |
  5. |   25   18.58179       640 |
     |---------------------------|
  6. |   30   18.80982     643.5 |
  7. |   35   19.05785   645.875 |
  8. |   40   19.26605    649.05 |
  9. |   45    19.3945     652.1 |
 10. |   50   19.72321    654.45 |
     |---------------------------|
 11. |   55   19.93005   656.675 |
 12. |   60   20.07934     659.4 |
 13. |   65   20.28437     662.4 |
 14. |   70   20.59594   664.425 |
 15. |   75   20.87183   666.675 |
     |---------------------------|
 16. |   80   21.08237   669.575 |
 17. |   85    21.4304     672.5 |
 18. |   90   21.87561     679.1 |
 19. |   95   22.64514     685.5 |
 20. |    .          .         . |
     +---------------------------+

. **************************************************************;
. ***** Correlation ******
> **************************************************************;
. cor str testscr;
(obs=420)

             |      str  testscr
-------------+------------------
         str |   1.0000
     testscr |  -0.2264   1.0000


. **************************************************************;
. ***** Equation 4.11 ******
> **************************************************************;
. reg testscr str, r;

Regression with robust standard errors                 Number of obs =     420
                                                       F(  1,   418) =   19.26
                                                       Prob > F      =  0.0000
                                                       R-squared     =  0.0512
                                                       Root MSE      =  18.581

------------------------------------------------------------------------------
             |               Robust
     testscr |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
         str |  -2.279808   .5194892    -4.39   0.000    -3.300945   -1.258671
       _cons |    698.933   10.36436    67.44   0.000     678.5602    719.3057
------------------------------------------------------------------------------

. **************************************************************;
. ***** Equation 4.33 ******
> **************************************************************;
. gen d = (str<20);

. reg testscr d, r;

Regression with robust standard errors                 Number of obs =     420
                                                       F(  1,   418) =   16.34
                                                       Prob > F      =  0.0001
                                                       R-squared     =  0.0369
                                                       Root MSE      =  18.721

------------------------------------------------------------------------------
             |               Robust
     testscr |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
           d |    7.37241   1.823578     4.04   0.000     3.787884    10.95694
       _cons |   649.9788   1.322892   491.33   0.000     647.3785    652.5792
------------------------------------------------------------------------------

. log close;
       log:  C:\EC471\ch4.log
  log type:  text
 closed on:  11 Dec 2003, 21:15:17
--------------------------------------------------------------------------------------------------------------