System Dependability Assessment Tool

Cost and quality of service analysis of production systems based on the cumulative downtime

“…As this is a random variable with a high variability, the performance metrics, i.e., cost and quality of service, should be assessed using its density function. In these conditions, the adoption of the usual Markovian hypothesis (e.g., in Zakarian (1997) or Brehm (1996)), may introduce very significant errors in the calculations and, consequently, lead to wrong design decisions (for a detailed discussion on this topic, see Nunes (2002) or Faria (2001)). …”

Representing user workarounds as a component of system dependability

“…In [Brehm96], system dependability is evaluated based on models constructed from the specified characteristics of each of its components, including software, hardware, and people. However, the underlying inputs to the model (particularly software and human error representations) do not seem to take into account the complex interactions these components can have with the rest of the system, and do not seem to encompass the fact that users can help the system as well as cause failures.…”