A shoe company wants to determine if the new tread on its top line of running shoes lasts longer than the original tread. The company recruits 50 runners for a study. Each runner will perform their typical workout wearing one shoe with the original tread on one foot and another shoe with the new tread on the other foot. The foot that wears the new type of tread will be decided by flipping a coin. After one month, the runner will wear the new type of tread on the opposite foot. At the end of the second month, the difference in tread wear open paren New minus Original close paren will be calculated. What type of sampling is described in this study?
Each runner tests both tread types, so the two wear measurements come from the same person and are naturally paired. The study compares the new and original tread by calculating a within-runner difference (New minus Original), making this paired data rather than two independent samples. The coin flip helps balance which foot wears each tread first.
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