A Systematic Approach to Planning for a Designed Industrial

Response response variable units normal operating

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Unformatted text preview: able Table 2. Response Response variable (units) Normal operating level and range Blade profile (inches) Nominal (target) + 1 x 10-3inches to + 2 x 10m3 inches at all points Surface finish Smooth to rough (requiring hand finish) Typically 0 to 10 Surface defect count Study. Variables Measurement precision, accuracyhow known? Relationship of response variable to objective u.E= 1 x 1O-5 inches Estimate mean absolute difference from target and standard deviation of difference Should be as smooth as possible from a coordinate measurement machine capability study Visual criterion (compare to standards) Visual criterion (compare to standards) TECHNOMETRICS, Must not be excessive in number or magnitude FEBRUARY 1993, VOL. 35, NO. 1 6 DAVID E. COLEMAN AND DOUGLAS condition (which motivates the experiment). Such a comparison might be used to derive “performance measures” from response-variable outcomes. For example, with CNC-machining, blade profile is a response variable, and it is compared to the target profile by computing differences at certain locations. Mean absolute difference and the standard deviation of the differences are performance measures for the various experimental conditions. They can be analyzed separately or by using the standard deviations to compute weights for the mean analysis. 5. Is preferably obtained by nondestructive and nondamaging methods so that repeated measures can be made and measurement error can be quantified. 6. Should not be near a natural boundary. Otherwise, the variable will not discriminate well. For example, it is hard to distinguish a yield of 99.5% from 99.8%, and it is hard to detect and distinguish contamination levels near 0. 7. Preferably has constant variance over the range of experimentation. There are other important characteristics of response variables that the experimenters may not have considered or communicated to the whole experimentation team. This sheet helps to draw them out: (a) current use, if any (col. 2); (b) ability to measure (col. 3)...
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