Here, you determine how proficient you are at this all-important part of statistics by explaining, 'The standard deviation is an important quality control tool for improving business processes. It tells you how spread apart the data is by measuring how far each observed value is from the mean (average). For all distributions, about 95 percent of the values are within two standard deviations of the mean.'

'On the Six Sigma Quality Control Curve, the line extends /- 3 sigmas from the mean or 3s from the centerline when it comes to a control chart and process limits, forming the basis of how Lean Six Sigma tools are used for reducing or eliminating variation and enhancing process control. Tolerance limits are set at 6s from the centerline in a control chart.'

Also, it can't hurt to be ready with a pen, paper, and calculator to show the formula for calculating the standard deviation, as well as the way to calculate Six Sigma for continuous and discrete data, too, if further explanation is required.