DOE introduction

The term experiment is defined as the systematic procedure carried out under controlled conditions in order to discover an unknown effect, to test or establish a hypothesis, or to illustrate a known effect .

The term experiment is defined as the systematic procedure carried out under controlled conditions in order to discover an unknown effect, to test or establish a hypothesis, or to illustrate a known effect .

When analyzing a process, experiments are often used to evaluate which process inputs have a significant impact on the process output, and what the target level of those inputs should be to achieve a desired result (output). Experiments can be designed in many different ways to collect this information. Design of Experiments (DOE) is also referred to as Designed Experiments or Experimental Design - all of the terms have the same meaning.

When analyzing a process, experiments are often used to evaluate which process inputs have a significant impact on the process output,

and what the target level of those inputs should be to achieve a desired result (output).

Experiments can be designed in many different ways to collect this information. Design of Experiments (DOE) is also referred to as Designed Experiments or Experimental Design - all of the terms have the same meaning.

Early example of experimental design In 1747, while serving as surgeon on HM Bark Salisbury , James Lind , the ship's surgeon, carried out a controlled experiment to develop a cure for scurvy .

In 1747, while serving as surgeon on HM Bark Salisbury , James Lind , the ship's surgeon, carried out a controlled experiment to develop a cure for scurvy .

Lind selected 12 men from the ship, all suffering from scurvy, and divided them into six pairs, giving each group different additions to their basic diet for a period of two weeks. The treatments were all remedies that had been proposed at one time or another.

Lind selected 12 men from the ship, all suffering from scurvy, and divided them into six pairs, giving each group different additions to their basic diet for a period of two weeks. The treatments were all remedies that had been proposed at one time or another.

They were: A quart of cider every day Twenty five gutts of elixir vitriol three times a day upon an empty stomach, One half-pint of seawater every day A mixture of garlic, mustard, and horseradish in a lump the size of a nutmeg Two spoonfuls of vinegar three times a day Two oranges and one lemon every day.

They were:

A quart of cider every day

Twenty five gutts of elixir vitriol three times a day upon an empty stomach,

One half-pint of seawater every day

A mixture of garlic, mustard, and horseradish in a lump the size of a nutmeg

Two spoonfuls of vinegar three times a day

Two oranges and one lemon every day.

The men who had been given citrus fruits recovered dramatically within a week. One of them returned to duty after 6 days and the other became nurse to the rest.

The men who had been given citrus fruits recovered dramatically within a week. One of them returned to duty after 6 days and the other became nurse to the rest.

The others experienced some improvement, but nothing was comparable to the citrus fruits, which were proved to be substantially superior to the other treatments.

The others experienced some improvement, but nothing was comparable to the citrus fruits, which were proved to be substantially superior to the other treatments.

In this study his subjects' cases "were as similar as I could have them", that is he provided strict entry requirements to reduce extraneous variation. The men were paired, which provided replication. From a modern perspective, the main thing that is missing is randomized allocation of subjects to treatments.

In this study his subjects' cases "were as similar as I could have them", that is he provided strict entry requirements to reduce extraneous variation. The men were paired, which provided replication. From a modern perspective, the main thing that is missing is randomized allocation of subjects to treatments.

Experimental design can be used at the point of greatest leverage to : reduce design costs by speeding up the design process, reducing late engineering design changes, and reducing product material and labor complexity.

Experimental design can be used at the point of greatest leverage 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.

Designed Experiments are also powerful tools to achieve manufacturing cost savings by

minimizing process variation and

reducing rework, scrap, and the need for inspection.

). There are three aspects of the process that are analyzed by a designed experiment: 1. Factors , or inputs to the process. Factors can be classified as either controllable or uncontrollable variables. In baking Cake the controllable factors are the ingredients for the cake and the oven that the cake is baked

). There are three aspects of the process that are analyzed by a designed experiment:

1. Factors , or inputs to the process. Factors can be classified as either controllable or uncontrollable variables. In baking Cake the controllable factors are the ingredients for the cake and the oven that the cake is baked

2. Levels , or settings of each factor. Examples include the oven temperature setting and the amounts of sugar, flour, and eggs for making cake 3 Response , or output of the experiment. In the case of cake baking, the taste, consistency, and appearance of the cake are measurable outcomes potentially influenced by the factors and their respective levels.

2. Levels , or settings of each factor. Examples include the oven temperature setting and the amounts of sugar, flour, and eggs for making cake

3 Response , or output of the experiment. In the case of cake baking, the taste, consistency, and appearance of the cake are measurable outcomes potentially influenced by the factors and their respective levels.

Purpose 1. Comparing Alternatives. The experiment(s) should allow us to make an informed decision that evaluates both quality and cost . In the case of our cake-baking example, we might want to compare the results from two different types of flour. If it turned out that the flour from different vendors was not significant, we could select the lowest-cost vendor. If flour were significant, then we would select the best flour..

1. Comparing Alternatives. The experiment(s) should allow us to make an informed decision that evaluates both quality and cost .

In the case of our cake-baking example, we might want to compare the results from two different types of flour. If it turned out that the flour from different vendors was not significant, we could select the lowest-cost vendor. If flour were significant, then we would select the best flour..

2. Identifying the Significant Inputs (Factors) Affecting an Output (Response) - separating the vital few from the trivial many . We might ask a question: "What are the significant factors beyond flour, eggs, sugar and baking?“ Identifying the Significant Inputs (Factors) Affecting an Output (Response) - separating the vital few from the trivial many . We might ask a question: "What are the significant factors beyond flour, eggs, sugar and baking?"

2. Identifying the Significant Inputs (Factors) Affecting an Output (Response) - separating the vital few from the trivial many .

We might ask a question: "What are the significant factors beyond flour, eggs, sugar and baking?“ Identifying the Significant Inputs (Factors) Affecting an Output (Response) - separating the vital few from the trivial many . We might ask a question: "What are the significant factors beyond flour, eggs, sugar and baking?"

3. Achieving an Optimal Process Output (Response). "What are the necessary factors, and what are the levels of those factors, to achieve the exact taste and consistency of Mom's chocolate cake?

3. Achieving an Optimal Process Output (Response). "What are the necessary factors, and what are the levels of those factors, to achieve the exact taste and consistency of Mom's chocolate cake?

4. Reducing Variability. "Can the recipe be changed so it is more likely to always come out the same?" 5. Improving process or product "Robustness" - fitness for use under varying conditions. "Can the factors and their levels (recipe) be modified so the cake will come out nearly the same no matter what type of oven is used?"

4. Reducing Variability. "Can the recipe be changed so it is more likely to always come out the same?"

5. Improving process or product "Robustness" - fitness for use under varying conditions. "Can the factors and their levels (recipe) be modified so the cake will come out nearly the same no matter what type of oven is used?"

A well-designed experiment is: as simple as possible – obtaining the required information in a cost effective and reproducible manner.

A well-designed experiment is:

as simple as possible –

obtaining the required information in a cost effective and reproducible manner.