6160sigma160bb黑帶培訓(xùn)資料-160160booster_wk1_03_msa-文庫吧資料
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【正文】 must measure each unit the same number of times ? It is extremely desirable to randomize the order of the units and not let the operator know which unit is being measured ?Minitab looks at the total variation in the items or units measured 19 How a Gage Ramp。R ?The Gage Ramp。R Study Works ? m is pared with t in ?%Ramp。R study pares several repeated measurements by different operators on several parts. ?Then Minitab uses Analysis of Variance (see Hypothesis Testing module) to separate out measurement Repeatability amp。R Study 15 0 50 1000 . 0 00 . 0 10 . 0 20 . 0 30 . 0 40 . 0 50 . 0 60 . 0 70 . 0 8I n d5n??pmThe Gauge R amp。 R s t u d y(Se cti o n 2 )3 . Rep r o d u cib i l i t y Hav e m an y p eo p l e(i n str u m en t s o r l a b s ) *m ea s u re t h e s am e s am p l ere p ea t e d l yGag e Ramp。 Accuracy 2 You Are Here IMPROVE Gage Ramp。Measurement System Validation Gage Ramp。R Gage Linearity amp。R Review 4 List Common Problems With Measurements You Deal With ? ? ? ? ? ? ? 5 Common Problems with Measurements Problems with the measurements themselves 1. Bias or inaccuracy: The measurements have a different average value than a ―standard‖ method. 2. Imprecision: Repeated readings on the same material vary too much in relation to current process variation. 3. Not reproducible: The measurement process is different for different operators, or measuring devices or labs. This may be either a difference in bias or precision. 4. Unstable measurement system over time: Either the bias or the precision changes over time. 5. Lack of resolution: The measurement process cannot measure to precise enough units to capture current product variation. 6 Desired Measurement Characteristic for Continuous Variables Good accuracy if difference is small Standard value Observed value Data from repeated measurement of same item Good repeatability if variation is small * 1. Accuracy The measured value has little deviation from the actual value. Accuracy is usually tested by paring an average of repeated measurements to a known standard value for that unit. 2. Repeatability The same person taking a measurement on the same unit gets the same result. 7 Desired Measurement Characteristic for Continuous Variables, cont. 3. Reproducibility Other people (or other instruments or labs) get the same result you get when measuring the same item or characteristic. * Small relative to a) product variation and b) product tolerance (the width of the product specifications) D ata from Pa rt XD ata Co llector 1D ata Co llector 2Good reprodu cib il ity if diffe re nce is sm all *D ata from Pa rt X8 Desired Measurement Characteristic for Continuous Variables, cont. 4. Stability Measurements taken by a single person in the same way vary little over time. * Small relative to a) product variation and b) product tolerance (the width of the product specifications) * 9 Desired Measurement Characteristic for Continuous Variables, cont. 5. Adequate Resolution There is enough resolution
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