Linear Statistical Models: Regression

Prediction Practice: Part 3


1) For the categorical variable prog consider the following:
xi: regress write i.prog

      Source |       SS       df       MS              Number of obs =     200
-------------+------------------------------           F(  2,   197) =   21.27
       Model |  3175.69786     2  1587.84893           Prob > F      =  0.0000
    Residual |  14703.1771   197   74.635417           R-squared     =  0.1776
-------------+------------------------------           Adj R-squared =  0.1693
       Total |   17878.875   199   89.843593           Root MSE      =  8.6392

------------------------------------------------------------------------------
       write |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
    _Iprog_2 |    4.92381   1.539279     3.20   0.002     1.888231    7.959388
    _Iprog_3 |  -4.573333   1.775183    -2.58   0.011    -8.074134   -1.072533
       _cons |   51.33333   1.287853    39.86   0.000     48.79359    53.87308
------------------------------------------------------------------------------
a) Interpret the value of the constant (_cons).


b) Interpret the value _Iprog_2.


2) Consider the following regression results

a) Write the regression prediction equation for math'.



b) What is the predicted math score for a student with a read score of 40 and a write score of 40?


Linear Statistical Models Course

Phil Ender, 18dec99