Reliability block diagram (RBD)

A drawing with blocks for each element of a system and connecting lines representing the series, parallel, and more complex relationships between elements. Statistically, an RBD contains the probability of success (reliability) information for each block. For a single point in time (e.g., the warranty period), the probability may be a single number. The probability of success could also be a reliability function based on distributions or nonparametric models. RBDs provides a structure to perform reliability allocation and are also useful to gather reliability measurements to estimate system reliability or to identify elements for improvement priority.