The Reliable Engineer Primer (Cover title: CRE primer)
By Robert A Dovich, Bill Wortman, Quality Council of Indiana, Published by Quality Council of Indiana, 1995
Page VI-9 says, ". . .in series systems, the failure rate are additive; MTBF values are not!"
When writing a requirement for system availability, is there a minimum time period that should be specified for statistical significance?
For example, "The ABC system shall provide 99.95% availability, per quarter." Is "per quarter" too short? Should this be "one year"?
