The number of people needed to archieve statistically significant results more or less solely relies on the size of the effect that gets measured[1]. It's actua

The number of people needed to archieve statistically significant results more or less solely relies on the size of the effect that gets measured[1]. It's actually not unusual to design experimental studies with just a single person - provided the "treatment" (shaven legs in this case) are reversible. Then you just have to make repeated phases with and without treatment , e.g. ABABAB or even ABACABAC if you have an alternative treatment you want to compare the results with. [1] If you design a study you can actually start from the other end: If you can estimate the size of the effect to be measured, you can calculate the number of people needed for significance beforehand.