Work out test coverage (fault) instantly with clear inputs, formula shown and shareable results.
Fault coverage is detected faults over testable faults. The Williams-Brown model links it to defect escapes: DL = 1 - (1 - Y)^(1-T), which shows why coverage must reach 99%+ for automotive parts — at 95% coverage and 2% incoming defects, thousands of parts per million escape.
Defect level
DL = 1 - (1 - defect level)^(1 - coverage); coverage = detected / testable faults
Because escapes fall roughly exponentially with coverage. Going from 98% to 99.5% can cut DPPM by a factor of four.
Redundant logic, unreachable states and structures excluded by design-for-test constraints. They are excluded from the coverage denominator but must be justified.