Bioequivalence and Bioavailability Forum • V corrected

V corrected [🇷 for BE/BA]

posted by d_labes – Berlin, Germany, 2011-01-28 15:12 (4836 d 01:50 ago) – Posting: # 6508
Views: 64,366
(edited by d_labes on 2011-01-28 15:32)

Dear ElMaestro,

I think your V needs to be corrected to reflect the FDA model for replicate cross-over designs.
See Patterson et al
"REPLICATE DESIGNS AND AVERAGE, INDIVIDUAL, AND POPULATION BIOEQUIVALENCE"
GSK BDS Technical Report 2002 – 01
online resource

It has to be composed from these two parts:
(sequence TRTR, hope I got all these nasty subscripts right :cool:

)
between-subject:

v_BT cov_TR v_BT cov_TR cov_TR v_BR cov_TR v_BR v_BT cov_TR v_BT cov_TR cov_TR v_BR cov_TR v_BR

and within-subject diagonal matrix:

v_WT v_WR v_WT v_WR

I'm not so familiar with the so-called V matrix but I guess its the sum of both?^{*see PS}
Thus you have 5 variance-covariance parameters to estimate:

v_BT, v_BT and cov_TR from the between-subject variation
v_WT and v_WR from the within-subject part

In your model/abbreviated output I only identify 4 covariance parameters:
v_BT, v_BT and cov_TR, latter here given as Corr(elation) and one residual error term which is presumable the mean of v_WT and v_WR or other spoken common within-subject error (assuming v_WT = v_WR=v_e).

Have a look at the very beginning of this thread to see that FDA's Proc MIXED and my lme() attempt are giving the same covariance parameter values (except that Proc MIXED gives variances/covariances and lme() stddev's for the between part and an error term and factors for T/R for the within-subject part, i.e. you have to calculate f.i. s_WR as error(residual) term multiplied by the factor for R.

^*PS: Regarding the matratzes we had it already here.
[edit]----------------------------
link to technical report corrected

—
Regards,

Detlew

Complete thread:

Freedom for replicate bears d_labes 2009-04-17 12:06 [🇷 for BE/BA]
- Freedom for replicate bears ElMaestro 2009-04-17 14:50
  - Contain does not contain d_labes 2009-04-17 15:07
- Freedom for replicate bears ElMaestro 2009-04-18 03:45
  - Freedom incompatible with baseball bats d_labes 2009-04-20 08:42
- Freedom for replicate bears yjlee168 2009-04-19 21:38
  - Freedom to some degree d_labes 2009-04-20 08:30
    - Freedom to some degree yjlee168 2009-04-21 14:03
      - FDA loves replicate bears? d_labes 2009-04-21 16:11
        
        Cholesky factor ?! Helmut 2009-04-22 00:46
        
        Cholesky factor ?! d_labes 2009-04-22 11:20
        
        FDA loves replicate bears? yjlee168 2009-04-23 08:08
        
        FDA loves SAS code? d_labes 2009-04-23 09:48
        
        FDA loves SAS code? definitely. yjlee168 2009-04-23 10:46
        
        SAS? or R? or what? d_labes 2009-04-23 15:07
        
        SAS? or R? or what? Helmut 2009-04-23 15:25
        
        SAS? or R? or what? d_labes 2009-04-23 16:06
        
        SAS? or R? or what? Helmut 2009-04-23 16:30
        
        SAS? YES; R? why not? as long as they are useful... yjlee168 2009-04-23 19:56
        
        New Forum-Category 'bear'? Helmut 2009-04-23 20:03
        
        New Forum-Category 'bear'? yjlee168 2009-04-23 20:19
        
        New Forum-Category 'R for BE/BA' Helmut 2009-04-23 20:37
        
        New Forum-Category 'R for BE/BA' yjlee168 2009-04-24 09:19
        
        Replicated again d_labes 2009-04-24 08:27
        
        Replicated again yjlee168 2009-04-24 09:26
- getting decimals ElMaestro 2010-06-03 05:21
  - getting decimals yjlee168 2010-06-03 08:37
    - getting decimals ElMaestro 2010-06-04 01:59
- Freedom for replicate bears ElMaestro 2011-01-27 21:50
  - lmer vs. lme d_labes 2011-01-28 09:02
    - lmer vs. lme ElMaestro 2011-01-28 09:42
      - lmer vs. lme d_labes 2011-01-28 11:37
        
        V ElMaestro 2011-01-28 12:14
        
        V correctedd_labes 2011-01-28 14:12
        
        V corrected ElMaestro 2011-01-28 15:20
        
        Peculiar partial replicate d_labes 2011-01-28 16:10