6160sigma160bb黑帶培訓(xùn)資料-160160booster_wk1_03_msa(已修改)
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【正文】 Measurement System Validation Gage Ramp。R Gage Linearity amp。 Accuracy 2 You Are Here IMPROVE Gage Ramp。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 in the measurement device so that the product can have many different values. 5 .1 5 . 2 5 . 3 5 . 4 5 . 5X XXXXXXXXXXXXXXXGood if 5 or more distinct values are observed 10 Improving a Measurement System A measurement system consists of ? Measuring devices ? Procedures ? Definitions ? People To improve a measurement system, you need to ?Evaluate how well it works now (by asking ―how much of the variation we see in our data is due to the measurement system?‖) ? Evaluate the results and develop improvement strategies 11 Ways to See if the Measurement System is Adequate Te s t f o r How Te s t Na m e1 . A cc u ra cy Tes t f o r t h e a m o u n t o fb i a s t h r o u g h o u t t h ep rod u c t rang e b yre p ea t e d l y m ea s u r i n g― k n o wn ‖ qua n titie
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