Repeatability & Reproducibility - PowerPoint PPT Presentation

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

• 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:

• 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

&

are called:

gauge repeatability and reproducibility studies

(gauge R&R studies).

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

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!

Reproducibility = Appraiser Variation

Standard deviation for Reproducibility

זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י המפעילים!

זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י מערכת המדידה!