Bioequivalence and Bioavailability Forum • Getting variance components

Getting variance components [🇷 for BE/BA]

posted by d_labes – Berlin, Germany, 2017-02-07 12:16 (3055 d 20:27 ago) – Posting: # 17029
Views: 19,581

Dear StatR,

❝ ... More clearly, I want to extract between subject variances (sigmaBT^2, sigmaBR^2), within subject variances (sigmaWT^2, sigmaWR^2) under the test and reference formulation, also subject-by-formulation interaction (sigmaD^2 = sigmaBT^2 + sigmaBR^2 - 2*rho*sigmaBT*sigmaBR).

What is needed for that goal is to formulate a model which have these variance-covariance parameters.
Your model is one with assuming sigmaWT = sigmaWR and sigmaBT=sigmaBR, rho=1.
Thus you have only two variance-covariance parameters in your output above:

Random effects:

 Groups   Name        Std.Dev.

 Sequence (Intercept) 0.002309 # sigmaBT = sigmaBR

 Residual             0.356224 # sigmaWT = sigmaWR

Unfortunately there is currently no way to formulate a model similar to the FDA code for replicate designs within package lme4 / lmer(). See f.i. this post for more details on the why.

In the older package nlme / lme() you may formulate the model similar to the FDA code. See that post.
But nevertheless you can't get the 'correct' CI from that R solution since the degrees of freedom for the contrast T-R are different to that of SAS Proc MIXED.

Hope this helps.

—
Regards,

Detlew

Complete thread:

Bear vs. Phoenix & SAS Helmut 2015-04-20 17:34
- R vs. Phoenix & SAS? yjlee168 2015-04-20 19:36
  - R vs. Phoenix & SAS? Helmut 2015-04-21 01:02
    - lme() does not work with all fixed effects yjlee168 2015-04-21 23:41
      - lme() does not work with all fixed effects Astea 2016-11-04 00:13
        
        lmer: Method B (PE catched for imbalanced dataset!!!) and Method C mittyri 2016-11-05 17:38
        
        lmer: Method B (PE catched for imbalanced dataset!!!) and Method C Astea 2016-11-05 19:27
        
        lmer: Method B is ready for scaling mittyri 2016-11-05 20:01
        
        lmer: Method B is ready for scaling Astea 2016-11-06 11:50
        
        lmer: Method B is ready for scaling mittyri 2016-11-07 06:07
- info for lsmeans yjlee168 2015-04-20 21:34
  - info for lsmeans Helmut 2015-04-21 01:15
    - once more about R and replicate designes Astea 2016-11-02 23:43
      - once more about R and replicate designes VStus 2016-11-06 11:34
        
        Getting variance components from the lmer output StatR 2017-02-03 13:53
        
        Getting variance components from the lmer output VStus 2017-02-03 15:47
        
        Getting variance components from the lmer output StatR 2017-02-03 17:12
        
        Getting variance componentsd_labes 2017-02-07 11:16
        
        Getting variance components StatR 2017-02-07 11:36
        Getting variance components StatR 2017-02-08 08:41
        
        Getting variance components d_labes 2017-02-08 10:13
        
        Getting variance components StatR 2017-02-08 10:19
        
        Data structure Helmut 2017-02-08 10:33
        
        Data structure StatR 2017-02-08 10:49