Weibull & Reliability Analysis - Modified Failure Order for Multiple-Censored Data

For multiple-censored data, a weighted average ordered failure is calculated for each failure after the first censored data point. These failure orders are then used to compute the median rank, to estimate the cumulative distribution function. For single-censored data and data without censoring, refer to the description of the options in Failure Order.

The modified failure order j is computed as (see Dodson 1994):

I_j = ((n+1)-O_p )/(1+c)

where:

Ij is the increment for the j ^th failure

n is the total number of data points

Op is the failure order of the previous observation (and O_j = O_p +I_j)

c is the number of data points remaining in the data set, including the current data point

The median rank is then computed as:

F(t) = (I_j -0.3)/(n+0.4)

where I_j denotes the modified failure order, and n is the total number of observations.