IEC 60493-1:2011 gives statistical methods which may be applied to the analysis and evaluation of the results of ageing tests. It covers numerical methods based on mean values of normally distributed test results. These methods are only valid under specific assumptions regarding the mathematical and physical laws obeyed by the test data. Statistical tests for the validity of some of these assumptions are also given. This standard deals with data from both complete test sets and censored test sets. This standard provides data treatment based on the concept of data sub-group as defined in Clause 3. The validity of the coefficients used in the calculation processes to derive statistical parameters of the data groups are described in IEC 60216-1. This second edition cancels and replaces the first edition, published in 1974, and constitutes a technical revision. The main changes with respect to the first edition are that, besides a complete editorial revision, censored data sub-group are considered.