Statistical Confidence - If a population of process related measurements or manufacturing errors (or any associated machine state) are determined to be statistical in nature, this statement relates the percentage of measurements or parts that would fall within a stated range. For a particular statistical relation, such as gaussian, the uncertainty may include a mathematical parameter such as "The 3 sigma confidence for accuracy is 5 micrometers" etc (95% of parts would have accuracy less than 5 micrometers). The statistical nature of measurement or manufacture errors is related to the performance or process repeatability.