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Repeatability & Reproducibility. הישנות ו הדירות. Repeatability and Reproducibility (R & R) Studies Evaluate the precision of a measurement system. It is important that the gauge be properly calibrated Before starting the Gauge R & R Study. Precision and Accuracy. Precision
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Repeatability & Reproducibility הישנות ו הדירות Repeatability and Reproducibility (R & R) Studies Evaluate the precision of a measurement system. It is important that the gauge be properly calibrated Before starting the Gauge R & R Study.
Precision Is the closeness of agreement between randomly selected individual measurement or test results. Precision Repeatability Problem: The same person (or station) can’t get the same result twice on the same subject Reproducibility Problem: Different people (or stations) can’t agree on the result obtained on the same subject Within Inspector Error between Inspector Error
Gauge Repeatability & Reproducibility • Gage R&R is a study to measure the measurement error in measurement systems. • The 10% rule tells us that if the percent of tolerance consumed by the R&R does not exceed 10%, the measurement system is excellent. • R&R = 15% means that 15% of the variation in product measurements is due to the measurement System.
Total observed variance • Each independent component of the model is variable: • Product quality characteristic - • Gauge, measurement error - • Total observed variance in product quality characteristic measurements:
Gauge variance • If more than one operator used in study then measurement (gauge) error has two components of variance: • Repeatability: • - Variance due to measuring instrument • Reproducibility: • - Variance due to different operators
Experiments to estimate the components & are called: gauge repeatability and reproducibility studies (gauge R&R studies).
Repeatability & Reproducibility Report n - number of parts r – number of operators For example : 2 operators, r=2 j=1…r 10 items , n=10 i=1…n
Average and Range method Repeatability = Equipment Variation Standard deviation for Repeatability Where d2 is a factor that depends on the number of trials (sample size): זהו החלק של השונות, בטווח הסיבולת, הנגרמת ע"י הציוד!
Average and Range method Reproducibility = Appraiser Variation Standard deviation for Reproducibility זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י המפעילים!
Combined Gage Variation זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י מערכת המדידה!