The ability to understand and predict product performance is important to all manufacturers but especially manufacturers of electronic and optical devices where a high level of product consistency and performance is required. Identification of the errors that reduce product performance is usually done at considerable cost through design experiments or a Taguchi analysis (for details, see Taguchi Methods, Glen Stuart Peace, Addison-Wesley publishing Company, In 1992). Integrated circuit and laser fabrication processes often operate at near optimum conditions. Under such conditions non-Gaussian distributions are often observed for variable processes or product characteristics.
In the conditions where the process is operating at near optimum conditions a Chi-square analysis is appropriate. A method for assessing the contributions to the variability and an avenue to eliminating them is required to optimize a product characteristic or manufacturing process.