As life data is collected, it must be arranged so that the lowest failure time (earliest-occurring failure) is listed first and the highest failure time (latest-occurring failure) is listed last. This ranking sets up the plotting positions for the time (t) axis and the ordinate, F(t), in percentage values. Each failure is to be plotted at its time-to-failure (t) and an estimate of F(t), the percentage of the total population failing before it.