# Interpret the key results for Evaluate Measurement Process (EMP Crossed)

## Step 1: Use the EMP statistics to classify the measurement system

Use the EMP statistics to determine whether the measurement system is good enough to use for process improvement activities. The Classification Guidelines table gives the probabilities of warning for an X-bar chart to have an out-of-control point within ten subgroups for test 1 or for tests 1, 5, 6 and 8. First-class and second-class measurement systems are usually good enough to use for process improvement activities with an X-bar chart that uses test 1. Third-class measurement systems are usually good enough to use for process improvement activities with an X-bar chart that uses rules 1, 5, 6, and 8.

## Step 2: Use the charts to identify improvement opportunities

Use the charts to identify opportunities to improve the measurement system.
Repeatability chart by operator
Shows whether any points fall above the upper control limit.

If the operators measure consistently, the points will fall within the control limits.

Signal-to-noise chart by operator
Shows whether most points fall beyond the control limits.

The parts that you choose for a gage study should represent the typical part-to-part variability. Thus, you should expect more variation between part averages, and the graph should show that most points fall beyond the control limits.

Parallelism plot
Shows whether the lines that connect the measurements from each operator are similar or whether the lines cross each other.

Lines that are coincident indicate that the operators measure similarly. Lines that are not parallel or that cross indicate that an operator's ability to measure a part consistently depends on which part is being measured. A line that is consistently higher or lower than the others indicates that an operator adds bias to the measurement by consistently measuring high or low.

Analysis of main effects (ANOME)
Shows whether differences between operators are small compared to the differences between parts.

Points within the decision limits indicate that the mean measurements for each operator are similar.

Analysis of mean ranges (ANOMR)
Shows whether operators measure consistently compared to each other.

Points within the decision limits indicate that the mean ranges for each operator are similar.