Bioequivalence and Bioavailability Forum • Data structure

Data structure [🇷 for BE/BA]

posted by Helmut – Vienna, Austria, 2017-02-08 11:33 (3055 d 02:31 ago) – Posting: # 17036
Views: 19,646

Hi StatR,

❝ Subject Formula Period Sequence Yijk

❝ 1 1 1 1 4.933014

❝ 1 0 2 1 5.006829

❝ 1 1 3 1 4.854162

❝ 1 0 4 1 5.081755

❝ ...

❝

❝ Where Yijk is the PK characteristic. The first sequence represents "TRTR" and the second sequence: "RTRT". In the formula 1 = T and 0 = R.

Only a general remark about data structures in R. I suggest to code categorial (classification) variables as characters instead of numeric (Treatment, Sequence). It not only helps others to understand what you have meant without requiring an explanation (1=TRTR, 2=RTRT and 1=T, 0=R) but also models (e.g., lm(), lme(), lmer()) will automatically treat them as factors. Avoid Formula and use Treatment or Formulation instead. Personally I prefer Treatment over Formulation for generality (imagine a food-effect study where we have the same formulation).
Convert numeric variables (except the PK-response) to factors as well:

data$Subject <- as.factor(data$Subject) data$Period <- as.factor(data$Period)

❝ Unfortunately, I am confused after reading tons of post, and I could not figure out what is "trt", "tmt" ...

Always the treatment is meant. To add confusion in package bear Yung-jin uses drug. ;-)

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Helmut Schütz

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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 components d_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 structureHelmut 2017-02-08 10:33
        
        Data structure StatR 2017-02-08 10:49