A dogleg is a sharp change of slope in Weibull-plotted data, so the points form two straight segments instead of one. It usually means the sample mixes failure modes, such as early defects and later wear-out, or mixes populations, such as two suppliers or a bad production batch among good ones. The fix is to split the failures by mode or batch using teardown reports and fit each group on its own.
Bearing data has a dogleg at about 800 hours. Teardown says the early ones are all contamination, so split the fit.
Also heard as
- hockey stick
- bend
Related terms
Weibull distribution
Flexible life distribution with a shape and a scale parameter, the standard model for fitting time-to-failure data.
Shape parameter
Weibull beta: the slope of a Weibull plot, which shows whether failures are early-life, random or wear-out.
Infant mortality
Early-life failures caused by manufacturing flaws, giving a failure rate that starts high and then falls.
Censoring
Incomplete life data where a unit's exact failure time is unknown because the test ended or the unit was removed first.