Bioequivalence and Bioavailability Forum • Proc GLM with missings

Proc GLM with missings [Outliers]

posted by d_labes – Berlin, Germany, 2013-08-07 16:46 (3911 d 23:26 ago) – Posting: # 11233
Views: 10,426

Dear Helmut!

❝ ... Note that PROC GLM will always drop the entire subject even if you kept the other periods in the data set.

This is an widely spread rumour, also here in the forum. But nevertheless isn't true :no:

.

Here an example: 3x6x3 data of 12 subjects with one subject in one period set to missing.
Proc GLM output:

                                    The GLM procedure

                      Analysis of Variance - Tests of Model Effects

                                             

   Source               DF              SS     Mean Square    F Value    Pr > F



   treatment             2        0.024103        0.012051       1.00    0.3873

   period                2        0.005885        0.002942       0.24    0.7863

   subject(sequence)     6        0.439062        0.073177       6.06    0.0011

   -----------------

   Error: MS(Error)     19        0.229576        0.012083                     

   Error: MSE

 



   Source               DF              SS     Mean Square    F Value    Pr > F



   sequence              5        0.448448        0.089690       1.23    0.3991

   -----------------

   Error            6.0032        0.438708        0.073079                     

   Error: 0.9984*MS(subject(sequence)) + 0.0016*MS(Error)

df(subjects)= df(sequence)+df(subject(sequence))=11 (=N-1). All subjects used!
df(Error) = 2*N-4 = 20 if no missings, but here 1 missing i.e. =19. All data used!

What SAS does with the sequence effect test (random statement used) in such cases is left for discussion. Never understood it really.

—
Regards,

Detlew

Complete thread:

"Removal" of an outlier: subject vs period lechia 2013-08-06 23:23
- "Removal" of an outlier: subject vs period ElMaestro 2013-08-07 11:09
- Canada: subject, not period Helmut 2013-08-07 13:48
  - Proc GLM with missingsd_labes 2013-08-07 14:46
    - Proc GLM with missings jag009 2013-08-07 15:03
    - Proc GLM with missings Helmut 2013-08-07 15:21
      - Proc GLM with missings ElMaestro 2013-08-07 15:39
        
        Proc GLM with missings ElMaestro 2013-08-07 16:22
        Proc GLM random d_labes 2013-08-07 16:46
      - Proc GLM with missings for 2x2 crossover d_labes 2013-08-07 16:34
  - Canada: subject, not period lechia 2013-08-07 15:46
    - Canada: subject, not period Helmut 2013-08-07 15:57
  - Canada: subject, not period lechia 2013-08-12 15:48