Interpretation of a quality control chart is based on the fact that for a normal distribution:
A) 99% of the values are within 3 SD of the mean
B) 99% of the values are within 2 SD of the mean
C) 95% of the values are within 3 SD of the mean
D) 95% of the values are within 1 SD of the mean

Question

Quizplus · Accepted Answer

In a normal distribution, approximately 99.7% of the data falls within 3 standard deviations (SD) of the mean. This principle is foundational in the interpretation of quality control charts to determine if a process is in control or if there are outliers that need investigation.

Interpretation of a Quality Control Chart Is Based on the Fact