In ranked set sampling, we select $n$ random sets, each of size $n$. Then we choose the largest unit from the 1st set, 2nd largest from the 2nd set, and thus $n$th largest from the $n$th set. This sampling procedure was first introduced by McIntyre (1952). The reference is A method for unbiased selective sampling, using ranked sets. Australian Journal of Agricultural Research, 3(4), 385-390. In this paper, I am not understanding what did the author mean by
"distribution of samples of the same rank from sets of five random samples"
in figure 1. Especially, does
same rank mean the third distribution is a distribution of only third largest unit? If so, what is the interpretation of this bell shaped curve?