Bioequivalence and Bioavailability Forum • Confounded effects

Confounded effects [Design Issues]

posted by Helmut – Vienna, Austria, 2018-06-29 12:35 (1206 d 14:29 ago) – Posting: # 18998
Views: 4,968

Hi libaiyi,

» I am a little confused that do you mean that carryover may cause carryover effect and period effect at the same time?

See this post for examples: Two others here:

Period effect: 0%
Sequence (carryover) effects: RT +20%, TR +20%
period sequence sequence 1 2 means RT 100 114 107 TR 95 120 107.5 period means 97.5 117 107.25 treatment means R 110 T 104.5 T/R 95.00%
Unbiased treatment effect in the presence of a period effect.
Unbiased treatment effect in the presence of equal carryover effects.
Period effect: +10%
Sequence (carryover) effects: RT +10%, TR +10%
period sequence sequence 1 2 means RT 100 114 107 TR 95 120 107.5 period means 97.5 117 107.25 treatment means R 110 T 104.5 T/R 95.00%
Unbiased treatment effect in the presence of a period effect.
Unbiased treatment effect in the presence of equal carryover effects.

In a 2×2 design some effects are confounded (see what Detlew wrote above). Hence, if there are true and equal carryover effects, results are exactly the same as if there are none and only a true period effect (the second example in the other post).
I guess you could only sort it out with full replicate designs where you have sequences containing TT and RR (TRRT|RTTR, TTRR|RRTT, or TRR|RTT).

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Complete thread:

Significant period effect jag009 2016-12-20 04:48 [Design Issues]
- Significant period effect ElMaestro 2016-12-20 12:17
  - period x sequence d_labes 2016-12-21 10:45
    - period x sequence jag009 2016-12-21 22:21
  - Significant period effect libaiyi 2018-06-29 12:02
    - Confounded effectsHelmut 2018-06-29 12:35
      - Confounded effects libaiyi 2018-07-03 09:52