Suppose we have a left-truncated sample, with the data below a pre-specified threshold level H not recorded
(not observable). The observable data sample x = {x1, x2, ..., xn} has each data point at least as great as
H, and includes a total of n observations. Let {X(j)}1≤j≤n be a vector of the order statistics, such that
X(1) ≤ X(2) ≤ ... ≤ X(n)
. The empirical distribution function of the sample is defined as