PDF HOW TO USE MINITAB

HOW TO USE MINITAB: DESIGN OF

EXPERIMENTS

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Noelle M. Richard 08/27/14

CONTENTS

1. Terminology

2. Factorial Designs

When to Use? (preliminary experiments)

Full Factorial Design

General Full Factorial Design

Fractional Factorial Design

Creating a Factorial Design

Replication

Blocking

Analyzing a Factorial Design

Interaction Plots

3. Split Plot Designs

When to Use? (hard to change factors)

Creating a Split Plot Design

4. Response Surface Designs

When to Use? (optimization)

Central Composite Design

Box Behnken Design

Creating a Response Surface Design

Analyzing a Response Surface Design

Contour/Surface Plots

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Optimization

TERMINOLOGY

Controlled Experiment: a study where treatments are imposed on experimental units, in order to observe a response

Factor: a variable that potentially affects the response

ex. temperature, time, chemical composition, etc.

Treatment: a combination of one or more factors

Levels: the values a factor can take on

Effect: how much a main factor or interaction between factors influences the mean response

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TERMINOLOGY

Design Space: range of values over which factors are to be varied

Design Points: the values of the factors at which the experiment is conducted

One design point = one treatment Usually, points are coded to more convenient values ex. 1 factor with 2 levels ? levels coded as (-1) for low level and (+1) for high level

Response Surface: unknown; represents the mean response at any given level of the factors in the design space.

Center Point: used to measure process stability/variability, as

well as check for curvature of the response surface.

Not necessary, but highly recommended.

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Level coded as 0 .

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WHEN DO YOU USE A FACTORIAL DESIGN?

Factorial designs are good preliminary experiments

A type of factorial design, known as the fractional factorial design, are often used to find the "vital few" significant factors out of a large group of potential factors. This is also known as a screening experiment

Also used to determine curvature of the response surface

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