Visual Six Sigma: Making Data Analysis Lean

6.3. Collecting Data

Data collection is the usual focus of the Measure Phase of a Six Sigma project. Here, a team typically assesses the measurement systems for all key input and output variables, formulating operational definitions if required and studying variation in the measurement process. Once this is done, a team constructs a baseline for current process performance.

Relative to measurement processes, Sean is particularly concerned with the visual inspection that classifies parts as good or bad. However, prudence requires that measurement of the four Ys identified should also be examined. Sean asks the team to conduct MSAs on the three measurement systems: the backscatter gauge, the spectrophotometer, and the visual color inspection rating that classifies parts as good or bad.

6.3.1. Backscatter Gauge MSA

Since the capability of the backscatter gauge used to measure thickness has not been assessed recently, the team decides to perform its first MSA on this measurement system. The team learns that only one gauge is typically used, but that as many as 12 operators may use it to measure the anodize thickness of the parts.

Sean realizes that it is not practical to use all 12 operators in the MSA. Instead, he suggests that the team design the MSA using three randomly selected operators and five randomly selected production parts. He also suggests that each operator measure each part twice, so that an estimate of repeatability can be calculated. The resulting MSA design is a ...