In some reliability studies, the natural response is measured degradation. Degradation measurement, for some variables, is a destructive process. For example, to measure the strength of an adhesive, load is increased linearly until the adhesive fails. Adhesive strength is then defined as the applied load when the adhesive failed. Similar tests are done to measure dielectric strength by increasing voltage until the dielectric fails. Destructive degradation tests can be accelerated, for example, by aging units at higher-than-usual temperatures. Statistical methods have been developed to model destructive degradation data and make reliability inferences.