I am trying to figure out the appropriate method of collapsing two of four session conditions for a randomized crossover trial. We had four session conditions (a, b, c, d) and unfortunately discovered that the same condition was provided twice and we technically only have three unique session conditions (a, b, c/d). For the two session conditions that are the same (c and d), we want to collapse them to create a single session condition (c/d). However, the order each participant/dyad received session conditions in was random i.e. participant 1 could have received treatments in this order: a, c, d, b and participant 2 could have received treatments in this order: c, b, d, a. My initial thought was to take the results from the two session conditions that were the same (c and d) and calculate the average, but I feel that is not the most appropriate method. We essentially have a session condition that was repeated and two session conditions that were not. Appreciate any advice!
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