[Data File Sheet Name: DOEM 3.2]. To determine the best tire size for long-distance road cycling, a tire manufacturer is comparing the three commonly used tire sizes (23mm, 25mm and 28mm) for the road cycling. The experimenter selected 90 randomly chosen cyclists with very similar characteristics, including their body weight, height, power, etc., which can be comparable to identical but independent twins (identical and independent experimental units). The experimenter collected a long-distance 50-mile training ride data, including both the average speed and the subjective rating of their perceived discomfort for all three tire sizes. The diagnostic analysis shows which of the assumption violations with respect to the discomfort rating?
