UNDERSTAND THE CONCEPT
The two-parameter Weibull reliability model is R(t) = exp[−(t/η)^β]. The scale η sets the time scale, while shape β describes how the modelled hazard changes with age: decreasing below one, constant at one and increasing above one.
A fitted curve needs failure ages, surviving observations and a justified population definition. Combining different failure mechanisms can distort interpretation. A shape estimate is evidence to investigate, not proof of a physical cause. Review fit and uncertainty before proposing a replacement interval.
Questions to take back to your team
- Are surviving observations included?
- Do the records share a plausible failure mechanism?
- Has fit uncertainty been reviewed before making an interval decision?
Further reading
Explore the primary references below. Requirements and applicability depend on your organization and jurisdiction.
