Can JMP 11 perform analysis of Time-varying Step Stress data? In a nutshell, we stress parts at a particular stress (let's say voltage) for an extended period of time. Some may fail, most will pass. We then increase the voltage (stress) for a shorter period of time. Again, some may fail, but most will pass. This increase of stress level and decrease of duration at that level continue until all (or perhaps only a portion) of the parts have failed.