Bioequivalence and Bioavailability Forum • Incomplete data, SAS9.2, DDF option residual

Incomplete data, SAS9.2, DDF option residual [🇷 for BE/BA]

posted by d_labes – Berlin, Germany, 2008-10-30 16:54 (6078 d 18:19 ago) – Posting: # 2612
Views: 33,636

Dear all,

after RTFM and reading tons of I-net places dealing with SAS Proc MIXED I am more confused as before.
For German speakers: "Da steh ich nun, ich armer Tor und bin genauso klug als wie zuvor!" (Johann W. von Goethe - Faust).

The only thing I could figure out was that DDFM=residual creates degrees of freedom which neglect totally the covariance structure of the random effects in the model. Not a good idea in case of data from x-over trials, I think.
But I couldn't figure out yet what this option is good for.

Interesting enough this DDFM was the default in SAS before Version 8. Thus users not aware of this had gotten inappropriate F-test!

For our data the consequence is: Simply forget it. The degrees of freedom are not appropriate anyhow. Full stop.

@for HS: Could it be that the DDF for the sequence effect was 22 instead of 21? Then WinNonlin method could be compared to SAS DDFM=contain or DDFM=betweenwithin.

—
Regards,

Detlew

Complete thread:

bear v2.0.1 (upwards) cont'd yjlee168 2008-10-26 20:46
- bear v2.0.1 (upwards) cont'd ElMaestro 2008-10-27 20:36
  - bear v2.0.1 (upwards) cont'd yjlee168 2008-10-28 08:59
    - bear v2.0.1 (upwards) cont'd ElMaestro 2008-10-28 09:49
      - Imbalance or incomplete data, SASophylistic view d_labes 2008-10-28 17:14
        
        Imbalance or incomplete data, SASophylistic view yjlee168 2008-10-29 07:36
        
        Incomplete cases d_labes 2008-10-29 09:24
        
        Incomplete cases yjlee168 2008-10-30 07:12
        
        Imbalance or incomplete data, SASophylistic view ElMaestro 2008-10-29 09:27
        
        Gold in discussion d_labes 2008-10-29 09:56
        
        Gold? Helmut 2008-10-29 13:03
        
        Imbalance or incomplete data, WinNonlin5.2.1 Helmut 2008-10-29 12:12
        
        Incomplete data, SAS9.2 d_labes 2008-10-29 16:38
        
        Missing values, imputation; separate study ElMaestro 2008-10-30 08:57
        Incomplete data, SAS9.2, DDF option residuald_labes 2008-10-30 15:54
        
        Never belief in any software you haven't written yourself Helmut 2008-10-30 16:30
        
        Imbalance or incomplete data, SASophylistic view yjlee168 2008-11-07 05:12
        
        Imbalance or incomplete data, SASophylistic view d_labes 2008-11-11 08:35
        
        Imbalance or incomplete data, SASophylistic view yjlee168 2008-11-11 08:54
        
        Imbalance or incomplete data, SASophylistic view d_labes 2008-11-11 13:13
        
        Imbalance or incomplete data, SASophylistic view yjlee168 2008-11-11 13:35
        
        Imbalance or incomplete data, SASophylistic view d_labes 2008-11-11 14:02
        
        Notification about new posts Helmut 2008-11-11 12:24
        
        Notification about new posts d_labes 2008-11-11 13:24
        
        3 Prerequisites for biostatistics Helmut 2008-11-11 13:39
        
        3 Prerequisites for biostatistics d_labes 2008-11-11 14:09