Is it possible to use the data collected during the washout period to verify that the length of the period was sufficient?
The carryover effect was not significant (we did not expect a carryover effect) and there were no effects of treatment.
I am interested in knowing whether the washout period was sufficient, and if I can shorten the washout period for future studies. For example, the washout period was 6 days for a behavioural study. It would save time and money to shorten the period to 4 days when we repeat the study.
I have data collected during the pre-study period (ie a baseline), during the washout periods, and during the periods when treatments were applied.
My thoughts were to compare the washout periods to the pre-study period, since everything was the same except treatments were not applied. To determine whether the washout period was sufficient (1), I would treat the 6 days within each washout period as a random effect. To determine whether I can shorten the washout period to 4 days (2), I would look to see if there are any trends/differences across the days.
However, I wonder if I cannot actually determine whether the washout period was significant because there were no significant effects of treatment.
