st: Re: Using margins

[Arti Rayit <arti.rayit@yahoo.com>]

Hello,
I am trying to teach myself how to use margins and I am using a simple oneway 
dataset from the manual.
. anova weight treatment
. margins treatment, post asbalanced
. test (1.treatment = 2.treatment) (1.treatment = 3.treatment) (1.treatment = 
4.treatment) (2.treatment = 3.treatment) (2.treatment = 4.treatment) 
(3.treatment = 4.treatment), mtest(bon)

 ( 1)  1bn.treatment - 2.treatment = 0
 ( 2)  1bn.treatment - 3.treatment = 0
 ( 3)  1bn.treatment - 4.treatment = 0
 ( 4)  2.treatment - 3.treatment = 0
 ( 5)  2.treatment - 4.treatment = 0
 ( 6)  3.treatment - 4.treatment = 0
       Constraint 2 dropped
       Constraint 4 dropped
       Constraint 5 dropped

---------------------------------------
       |        chi2     df       p
-------+-------------------------------
  (1)  |       63.83      1     0.0000 #
  (2)  |       16.13      1     0.0004 #
  (3)  |       17.26      1     0.0002 #
  (4)  |        9.80      1     0.0105 #
  (5)  |        8.95      1     0.0167 #
  (6)  |        0.02      1     1.0000 #
-------+-------------------------------
  all  |       64.37      3     0.0000
---------------------------------------
         # Bonferroni adjusted p-values

Yet when I run the example:
. oneway weight treatment,bon

                        Analysis of Variance
    Source              SS         df      MS            F     Prob > F
------------------------------------------------------------------------
Between groups      5295.54433      3   1765.18144     21.46     0.0013
 Within groups      493.591667      6   82.2652778
------------------------------------------------------------------------
    Total             5789.136      9   643.237333

Bartlett's test for equal variances:  chi2(3) =   1.3900  Prob>chi2 = 0.708

             Comparison of Average weight in grams by Fertilizer
                                (Bonferroni)
Row Mean-|
Col Mean |          1          2          3
---------+---------------------------------
       2 |   -59.1667
         |      0.001
         |
       3 |     -33.25    25.9167
         |      0.042      0.122
         |
       4 |      -34.4    24.7667      -1.15
         |      0.036      0.146      1.000
I get completely different adjusted probabilities.
What am I misunderstanding and doing wrong.
Arti



      

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/