Various embodiments provide systems, computer program products and computer implemented methods. Some embodiments include a system for modeling a relationship between a test time and a defect rate for a systematic multivariate issue caused by at least one predictable component and a random component in a semiconductor testing environment, the multivariate issue causing failure of a semiconductor device, the system that includes at least one computing device configured to perform actions including quantifying the at least one predictable component to produce at least one first mathematical form, quantifying the random component using distribution functions to produce a second mathematical form and producing a mathematical model of a relationship between the test time and the defect rate at a test condition by mathematically combining the at least one first mathematical form and the second mathematical form.