Statistical Background and Concepts
Ron Randall & Associates, Inc.
Ron Randall is an independent consultant specializing in applying the principles of Six Sigma quality.
Since the 1980s, Ron has applied Statistical Process Control and Design of Experiments principles to
engineering and manufacturing at Texas Instruments Defense Systems and Electronics Group. While at
Texas Instruments, he served as chairman of the Statistical Process Control Council, a Six Sigma Cham-
pion, Six Sigma Master Black Belt, and a Senior Member of the Technical Staff. His graduate work has
been in engineering and statistics with study at SMU, the University of Tennessee at Knoxville, and
NYU’s Stern School of Business under Dr. W. Edwards Deming. Ron is a Registered Professional Engi-
neer in Texas, a senior member of the American Society for Quality, and a Certified Quality Engineer.
Ron served two terms on the Board of Examiners for the Malcolm Baldrige National Quality Award.
Statistics do a fine job of enumerating what has already occurred. Industry’s most urgent needs are to
estimate what will happen in the future. Will the product be profitable? How often will defects occur?
The job of statistics is to help estimate the future based on the past.
When designing any part or system, it is necessary to estimate and account for the variation that is
likely to occur in the parts, materials, and product features. Statistics can help estimate or model the most
likely outcome, and how much variation there is likely to be in that outcome. From these models, esti-
mates of manufacturability and product performance can be made long before production. Knowledge
of the probabilities of defects prior to production is important to the financial success of the product.
Changes to the design or manufacturing processes that are completed prior to production are far less
costly than changes made during production or changes made after the product is fielded. Statistics can
help estimate these probabil