A Systematic Approach to Planning for a Designed Industrial

5 inappropriate confounding 6 inadequate measurement

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Unformatted text preview: ed. 5. Inappropriate confounding 6. Inadequate measurement precision sponses or factors 7. Unacceptable prediction error 8. Undesirable run order The experimenter’s lead to: of re- lack of statistical knowledge can 1. Inappropriate control-variable settings (e.g., range too small to observe an effect or range so large that irrelevant mechanisms drive the response variable) 2. Misunderstanding of the nature of interaction effects, resulting in unwisely confounded designs 3. Experimental design or results corrupted by measurement error or setting error 4. Inadequate identification of factors to be “held constant” or treated as nuisance factors. causing distorted results 5. Misinterpretation of past experiment results, affecting selection of response variables or control variables and their ranges 6. Lack of appreciation of different levels of experimental error, leading to incorrect tests of significance This article attempts to help bridge the gap by providing a systematic framework for predesign information gathering and planning. Specifically, we present @de sheets to direct this effort. The use of the guide sheets is illustrated through the (computer numerical control) CNC-machinery example briefly presented previously. This article is a consolidation and extension of the discussion by Hahn (1984), BOX et al. (197X), Montgomery (1991), Natrella (1979), Bishop. Petersen, and Traysen (1982), and Hoadley and Kettenring (1990). The guide sheets are designed to be discussed and filled out by a multidisciplinary experimentufion team consisting of engineers, scientists, technicians/operators, managers, and process experts. These sheets are particularly appropriate for complex experiments and for people with limited experience in designing experiments. The sheets are intended to encourage the discussion and resolution of generic technical issues needed before the experimental design is developed. Hahn TECHNOMETRICS, FEBRUARY 1993, VOL. 35, NO. 1 C. MONTGOMERY (1984) listed most of these issues and made the recommendation, “The major mode of communication between the experimenter and the statistician should be face-to-face disc...
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This document was uploaded on 02/12/2014.

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