Bioequivalence and Bioavailability Forum • Williams design 3-way

Williams design 3-way [Design Issues]

posted by Brus – Spain, 2021-06-11 14:19 (1039 d 16:03 ago) – Posting: # 22408
Views: 8,677

Dear Vezz and Helmut,

I think I understood Helmut. With my design (3x4x3), the carryover effect would be covered, since it generates balanced sequences for two-to-time comparisons, and any formulation is preceded equally often by each of the other formulations, but it does not cover the period effect, since that not all treatments are the same number of times in all periods (for example, in my design treatment "A" is administered 1 time in period 1, twice in period 2 and 1 time in period 3. In this way, in the event that there was a period effect, it would not be offset by the design and it would affect the results. Right?

As Vezz says, if you consider period effect in your model and the software itself already incorporates that correction in case there is period effect, you could have unbiased results, in fact, considering the period effect and the rest of possible effects (sequence, treatment,...) in the model, any design would be acceptable, right ?

But at this point, a question comes to mind, if our software is capable of calculating the period, sequence, group, and treatment effect, what need is there to make balanced designs?

In this way IMHO, and if I'm not mistaken, after kindly discussing it, I think the ideal option for a 3 treatment crossover study is 3x6x3 williams design.

Best regards,

Complete thread:

Three-way crossover BABE Studies acfalcao 2007-09-16 22:34 [Design Issues]
- Three-way crossover example data set Helmut 2007-09-17 20:47
  - Three-way crossover example data set acfalcao 2007-09-17 23:02
    - Three-way crossover example data set Helmut 2007-09-18 12:47
      - Three-way crossover (WinNonlin) Nirali 2007-09-21 06:49
        
        Three-way crossover (WinNonlin) Helmut 2007-09-21 13:04
        
        Three-way crossover (WinNonlin) Nirali 2007-09-25 08:05
        
        Three-way crossover (WinNonlin) Helmut 2007-09-25 13:15
      - Three-way crossover example data set Irene_I 2018-06-07 11:09
        
        Three-way crossover example data set Helmut 2018-06-07 13:04
        
        Three-way crossover example data set Irene_I 2018-06-08 11:09
        Three-way crossover example data set Irene_I 2018-06-12 09:21
        
        Leave-One-Out (IBD) Helmut 2018-06-12 12:42
        
        Leave-One-Out (IBD) Irene_I 2018-06-13 05:02
        
        Impact of pooled variance (bias, CI) Helmut 2018-06-13 15:02
        
        carry (over?) d_labes 2018-06-13 15:31
  - Pseudo-periods ElAlumno 2019-03-14 23:40
    - Pseudo-periods Helmut 2019-03-15 00:47
      - Two‐at‐a‐Time analysis in R ElAlumno 2019-03-22 21:59
        
        fixed & mixed (dammit!) and a request to SASians Helmut 2019-03-23 01:03
        
        Pooled vs IBD T-R in SAS from non-SASian mittyri 2019-03-23 23:13
        
        Pooled vs IBD T-R in SAS from non-SASian Helmut 2019-03-23 23:36
        
        mixed in R mittyri 2019-03-23 23:50
        
        mixed in R (EMA B ≠ FDA) Helmut 2019-03-24 01:23
  - Williams design 3-way Brus 2021-06-09 16:48
    - Williams design 3-way Helmut 2021-06-09 17:48
      - Williams design 3-way Brus 2021-06-10 14:33
        
        Williams design 3-way Helmut 2021-06-10 15:03
        
        Williams design 3-way vezz 2021-06-10 17:23
        
        Williams design 3-way Helmut 2021-06-10 20:14
        
        Williams design 3-way vezz 2021-06-11 09:11
        
        Williams design 3-wayBrus 2021-06-11 12:19
        Williams design 3-way Relaxation 2021-06-11 12:42
        
        Period effects in general Helmut 2021-06-11 15:41
        Williams design 3-way vezz 2021-06-11 16:56