Abstract: Described herein is a method for reject analysis for use in any process where rejects occur. The method comprises using the application of multivariate statistical process control techniques, and allows the rejects from a process to be controlled in a simple and effective manner by deriving the T2 statistic for a series of variables or classification categories that impact reject performance characteristics. The calculated T2 value is compared with a standard value for the particular system. If the value exceeds the critical value , it suggests that there has been a significant change in the typical reject rate compared with the expected situation and therefore appropriate action can be taken to identify the cause of the change and procedures can be put in place to correct the problems, that is, to return the reject rate to the expected position.

Abstract: Described herein is a method of controlling the effect of raw materials on manufacturability in which constituents in a product are controlled in a simple and effective manner prior to the constituents being committed to the manufacturing process for that product. This is achieved by deriving the T.sup.2 parameter from a number of important properties of the constituents which are known to impact performance characteristics of a final product, the derived T.sup.2 value being compared with a standard for that product. If the value of T.sup.2 exceeds a predetermined limit, there is an indication that there has been a significant change in the typical properties of the constituents and action can be taken to replace defaulting constituents prior to manufacturing. Replaced constituents can then be used at another time so as to avoid irretrievable loss, for example, waste.

Abstract: The present invention relates to the use of multivariate statistical process control as a means of process verification in photographic processes. The method of the present invention allows the process to be controlled in a simple and effective manner by deriving T.sup.2 for a series of variables which impact the material performance characteristics and comparing this value of T.sup.2 with a standard value for the particular system. The contributions of scores to T.sup.