There is a good discussion of degradation analysis in the NIST/SEMATEC Statistical Engineering Handbook. It refers to a book by Tobias and Trindade and one from Nelson for the methods and analysis. I have both books, and they are valuable.
We would like to find a standard, such as ISO, IEC, or ASTM for the method. It is easier for regulators to accept. I have not been able to identify one. The device is not medical electrical equipment, but IEC has a lot of reliability standards.
Do you know of a standard for degradation analysis?