Define & Measure (MSA)

In a Measurement System Analysis, what does 'repeatability' specifically measure?

• A The variation obtained when the same operator measures the same part repeatedly with the same gauge ✓
• B The difference between the gauge's average reading and a known reference value
• C The change in gauge bias across the operating range of the instrument
• D The variation between different operators measuring the same part

Answer: Repeatability (equipment variation) is the variation seen when one operator measures the same part multiple times with the same gauge under identical conditions.

In a Gage R&R study, 'reproducibility' refers to which source of variation?

• A Variation in the true values of the parts being measured
• B Variation in measurements caused by differences between operators (appraisers) ✓
• C Drift in the measurement system over an extended period of time
• D Variation from one appraiser repeating a measurement on the same part

Answer: Reproducibility (appraiser variation) is the variation in the average of measurements made by different operators using the same gauge on the same parts.

Using AIAG guidelines, a Gage R&R result expressed as % study variation of 8% indicates a measurement system that is:

• A Acceptable for use ✓
• B Acceptable only for sorting, not for process control
• C Unacceptable and must be rejected
• D Marginal and acceptable only with justification

Answer: AIAG guidelines classify %GRR below 10% as acceptable, 10-30% as marginal (conditionally acceptable), and above 30% as unacceptable.

The number of distinct categories (ndc) from a Gage R&R study should be at least what value for the measurement system to be considered adequate?

• A 10
• B 30
• C 2
• D 5 ✓

Answer: AIAG recommends ndc of 5 or greater, meaning the measurement system can reliably distinguish at least five distinct groups of parts.

A Gage R&R study reports a part-to-part standard deviation of 5.0 and a total Gage R&R standard deviation of 1.0. Using ndc = 1.41 x (part SD / Gage R&R SD), what is the number of distinct categories (rounded down)?

• A 14
• B 5
• C 6
• D 7 ✓

Answer: ndc = 1.41 x (5.0 / 1.0) = 7.05, which truncates to 7 distinct categories.

Which statistic is most appropriate for assessing an attribute (pass/fail) measurement system where multiple appraisers classify the same items?

• A Cohen's or Fleiss' Kappa agreement statistic ✓
• B Pearson correlation coefficient
• C Cp capability index
• D Gage linearity slope

Answer: Kappa measures inter-rater agreement beyond chance and is the standard statistic for attribute (categorical) measurement system analysis.