Bioequivalence and Bioavailability Forum

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).