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Stat-Ease by the Numbers

3 Textbooks written by the principals at Stat-Ease: The Simplified series of textbooks provides a practical guide to DOE for all experimenters.

5 Stat-Ease Academy E-Learning Topics: Users can learn basic statistics and how to use DOE without having to travel for an in-person workshop.

32 DOE workshops provided by Stat-Ease in 2022: Stat-Ease subject matter experts share their skills during hands-on, computer-intensive, DOE workshops, both in the United States and abroad.

29 Design-Expert & Stat-Ease 360 tutorials offered by Stat-Ease: From One-Factor Categoric to Response Surface Methods, Design-Expert users discover how to maximize the DOE software.

37 years since Design-Ease software was first developed (July 1985) by Stat-Ease.

45 Countries with Stat-Ease Partners/Distributors: From Bangalore to Luxembourg and beyond, click here to discover all of our international distributors.

Frequently Asked Questions

What is Design of Experiments?

What’s Design of Experiments (DOE)? It’s a branch of applied statistics created in the 1920s by Sir Ronald Fischer. DOE serves as a method to plan, conduct, analyze, and interpret controlled tests to evaluate the factors that control the value of a parameter or group of parameters. DOE is also referred to as Designed Experiments or Experimental Design—all of the terms have the same meaning. Experimental design is used to reduce design costs by speeding up the design process, reducing late engineering design changes, and reducing product material and labor complexity. Designed Experiments are also powerful tools to achieve manufacturing cost savings by minimizing process variation and reducing rework, scrap, and the need for inspection.

DOE is used to:

Reduce time to design and develop new products and processes.
Improve performance of existing processes.
Improve reliability and performance of products.
Achieve product and process robustness.
Perform evaluation of materials, design alternatives, setting component and system tolerances, and more.

How has Stat-Ease contributed to DOE?

Stat-Ease leaders first learned the benefits of DOE while working together at General Mills in its chemical research laboratory. Using an IBM PC, they created a menu-driven computer program that made DOE easy for non-statisticians. In April of 1985, with programming help from his colleague Tryg Helseth, Stat-Ease founder Pat Whitcomb completed the development of the first version of Design-Ease software.

Design-Ease provided the tools for factorial design and analysis. The next creation, Design-Expert software, provided innovative statistical tools for response surface methods as well as mixture optimization—a big attraction for users in the chemical process industries. In addition, statisticians at Stat-Ease have been active in developing new tools for design of experiments.

How is DOE used to improve a product or service?

DOE has many potential uses in improving processes and products. For example:

DOE enables an organization to compare alternatives. A tire company might use DOE to compare two different types of rubber and determine if the rubber from one vendor is better than another. It there is no significant difference, the company could select the lowest-cost vendor. The experiment allows the company to make an informed decision that evaluates both quality and cost.
DOE helps identify the significant inputs (factors) affecting an output (response)—separating the vital few from the trivial many. Scientists might ask: "What are the significant factors beyond rubber and friction?"
DOE helps achieve an optimal process output (response). "What are the necessary factors, and what are the levels of those factors, to achieve the best tire makeup for long-lasting tread wear?”
DOE reduces variability. "Can the make up of the rubber used for tire construction be changed so it wears evenly when in use?"
DOE minimizes, maximizes, or targets an output (response). "How can the rubber used to make tires be made more durably to avoid improper wear?"
DOE improves process or product robustness—fitness for use under varying conditions. "Can the factors used to make each tire be modified so the tires produced are always the same no matter what type of rubber is used?"
DOE balances tradeoffs when there are multiple critical to quality characteristics that require optimization. "How do you produce the best tire using the simplest process (least number of products) in the shortest possible time?"

Who uses DOE?

Statisticians and scientists use DOE to improve hundreds of products and services. Industries that benefit from DOE include:

Pharmaceuticals
Chemical
Industrial Process
Energy
Medical Products
Computer Hardware
Manufacturing
Agricultural
Biotech
Food
Plastics/Injection Molding
Etc...

How does DOE software simplify experimentation?

Software such as Stat-Ease 360 and Design-Expert enable multifactor DOE, which has replaced one-factor-at-a-time experimentation and lets statisticians solve complex factorial statistical equations. Computer software designed specifically for designed experiments became available from various leading software companies in the 1980s. Today, DOE software strengthens the capability to discern truths about experiments and statisticians attribute multifactorial DOE methods to providing more robust outcomes.

What Stat-Ease training is available to help statisticians?

Stat-Ease provides hands-on, computer-intensive, DOE workshops in the United States and abroad, both on-site and via distance learning. We help the first-time experimenter as well as the advanced practitioner with workshops that help individuals set up, analyze, and interpret DOE's ranging from fractional factorials to response surface designs; learn how to use mixture designs to develop statistical models of product performance; learn how to find optimal operating conditions with response surface methods, and more.