Outlier | Lean Six Sigma, Six Sigma Certification

An outlier is a data point that is located far from the rest of the data. Given a mean and standard deviation, a statistical distribution expects data points to fall within a specific range. Those that do not are called outliers and should be investigated to ensure that the data is correct. If the data is correct, you have witnessed a rare event or your process has changed. In either case, you need to understand what caused the outliers to occur.