The potential confounding of treatment-related effects in RI studies by litter (i.e., genetic effects) has been raised, because the RI does not always randomize the assignment of animals to treatment groups but often "assigns litters to the same dose group and uses all animals, while keeping track of litter identification information" (Bucher 2002).
These involved the random assignment of animals to treatment groups; blinded assessment of how the animals fared; a record of animals removed from the results, and a calculation to show that the study had enough animals to be statistically sound.
A better model would fit a true mixture model by computing posterior estimates of assignment of animals to groups.
The study design, including the assignment of animals to a respective group, is explained in Figure 1a.
Assignment of animals for MitoQ treatment was made in such a way that the animals of different experimental groups were age-matched during the study.
Tissues were evaluated using light microscopy by a veterinary pathologist blinded as to the assignment of animals to group or treatment.
All assessments were conducted by three trained testers (see Supplemental Material, Table S4) who were reliability-tested to a minimum 85% agreement every 6 9 months, and who were blinded to the assignment of animals to study groups.
For the semantic fluency task, participants named as many animals or fruits as possible in 1 min. Although we aimed to achieve an overall balance in the assignment of animals and fruits to L1 and L2, this was not possible because different testers were assigned to participants with different language pairs.
Assignments of animal and fungal cyclins to orthologous groups were extracted from KEGG Orthology [ 24, 25].
Slides were examined with standard bright-field microscopy (Olympus BX60) by a pathologist who was blinded to the assignment of the animal.
Behaviour was independently scored by two separate observers, one of whom was blind to the lesion group assignment of each animal.
