Design of Experiments

Design of Experiments


Experiments are designed and executed in order to illuminate our understanding about a product or process. Characteristics of products and processes are frequently affected by various factors. In an experiment, one or more process variables (or factors) are changed in order to observe the effect the changes have on one or more response variables. Classical experiments focus on varying one factor at a time (0FAT or 1FAT), perhaps at one or two levels, and attempt to hold everything else constant. Observed changes in these characteristics are then recorded for future consideration.

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Product Description

The series name has a double meaning:
(1) the spelling of the name r-e-l-e-a-s-e indicates that the series is intended to “release“ the non-expert down the path to reliable products and
(2) the complementary terms “REL” with “ease”, implying the series goal of “reliability made easy.”

Of course, reliability success is seldom easy, requiring expertise and tailoring with tradeoffs addressing life-cycle costs and other issues, but we hope that the series will help those not familiar with reliability practices understand the basics.

While it is unlikely that the reader will become an instant expert in reliability by reading the RELease guides, it is likely that he/she will gain a better appreciation of the basic tools that lead to designing and building reliability into products and systems. The number of pages in each guide is intentionally limited to address only the basics, with comprehensive authoritative references listed for those wanting to know more. The initial set of guides will be continuously expanded in the future. Please let us know how the series can be improved to meet your needs in introducing reliability to the non-expert, or suggest other topics you would like to see developed.

Additional information

File Type:



Richard Wisniewski





Publication Date:

December 2013

Table of Contents

1. What is Design of Experiments       2
  1.1. Cost-Benefit Tradeoff     3
2. Design of Experiments Terminology       3
3. The Process       4
  3.1. Applicable Methods     5
  3.2. Required Inputs     6
  3.3. Process Flow     7
  3.4. Applications and Tailoring     8
4. The Details       10
  4.1. Determine the Objective     10
  4.2. Determine the Process Variables     11
  4.3. Determine the Factor Levels     11
  4.4. Determine the Experimental Design     12
    4.4.1. Full-Factorial Designs   13
    4.4.2. Fractional-Factorial Designs   14
    4.4.3. Randomization   18
  4.5. Perform the Test     19
  4.6. Analyze the Data     19
5. Example       20
  5.1. Full-Factorial DOE Example     21
    5.1.1. Test Set-up   21
    5.1.2. Experiment Performance   22
    5.1.3. Data Analysis   23
    5.1.4. Experiment Conclusions   27
  5.2. Fractional-Factorial DOE Example     27
    5.2.1. Test Set-up   27
    5.2.2. Experiment Performance   28
    5.2.3. Data Analysis   28
    5.2.4. Experiment Conclusions   29
6. For More Information       30

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