We thank all of the participants for their compliments and their useful critiques of our paper and the Shainin System (SS). We also thank the editor and reviewers of this, and earlier versions, who contributed substantially to the paper. Due to space limitations we have addressed only a few of the more contentious issues raised by the discussants. To frame our response, we make the following three assumptions. First, in order to reduce variation in a specified output, we plan to follow Juran's diagnostic and remedial journeys. That is, we start by identifying one or more causes of the variation (the diagnosis), and then we seek a solution to remove or mediate against the effects of the identified causes (the remedy). Ledolter (JL) notes that this is common to all problem solving systems. Rereading Juran (always a good idea) on the steps in the diagnostic and remedial journeys (see Chapter 5 of Juran & Gryna, 1980), you will see a strong similarity to SS and some of the corresponding tools. Second, we define a cause of variation to be a process input that changes over realizations of the process, such as temperature, component dimensions in an assembly, cavity (in a multicavity moulding process), etc. An input that is fixed, such as a temperature set point or a control procedure, cannot be a cause of the output variation. Third, in the remedial journey, we must change the process to make an improvement. That is, we must change one or more inputs that are normally fixed, such as increase the temperature set point, or add a new error-proofing step to the control procedures.
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