class reliability.Probability_plotting.plotting_positions

Calculates the plotting positions for plotting on probability paper.

  • failures (array, list) – The failure data. Must have at least 1 element.
  • right_censored (array, list, optional) – The right censored failure data. Optional input. Default = None.
  • a (float, int, optional) – The heuristic constant for plotting positions of the form (k-a)/(n+1-2a) where k is the rank and n is the number of points. Optional input. Default is a = 0.3 which is the median rank method (same as the default in Minitab and Reliasoft). Must be in the range 0 to 1. For more heuristics, see:

(array(x),array(y)) (tuple) – a tuple of two arrays. The arrays provide the x and y plotting positions. The x array will match the failures parameter while the y array will be the empirical estimate of the CDF at each of the failures.


This function is primarily used by the probability plotting functions. The order of the input data is preserved (not sorted).