Comments on ‘Reliability and performance analysis for fault-tolerant programs consisting of versions with different characteristics’ by Gregory Levitin [Reliability Engineering and System Safety 86 (2004) 75–81]

This paper [Levitin G. Reliability and performance analysis for fault-tolerant programs consisting of versions with different characteristics. Reliab Eng Syst Safety 2004;86:75–81] presents a detailed reliability and performance analysis of fault-tolerant programs. Unfortunately, the treatment is dependent upon a key assumption: ‘Failures of versions for each component are statistically independent…’ (Section 2). Such an assumption is not justified.