Bioequivalence and Bioavailability Forum

Period effects in general [Design Issues]

posted by Helmut  – Vienna, Austria, 2021-06-11 15:41 (174 d 23:27 ago) – Posting: # 22410
Views: 2,730

Hi Relaxation and all,

» Now, lets both wait and see, whether I got it right .

You did.
In simple terms: In – any – crossover period effects mean out if (and only if) the number of treatments in each period are equal because then they are affected to the same extent.
That’s one of the reasons why we design studies for balanced sequences. Due to dropouts sequences may be imbalanced, which biases the outcome. However,

• unless the degree of imbalancedness is extreme, the bias is negligible and
  
• theoretically it would be possible to exclude subjects in order to get balanced sequences. That would mean a loss in power and it is ethically questionable since available data is discarded. Never saw it in practice.

—
Dif-tor heh smusma 🖖
Helmut Schütz


The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

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-way Brus 2021-06-11 12:19
                  • Williams design 3-way Relaxation 2021-06-11 12:42
                    • Period effects in generalHelmut 2021-06-11 15:41
                    • Williams design 3-way vezz 2021-06-11 16:56