Introduction to DOE

Introduction to DOE

1. Strategy of Experimentation

   • Experiment
     • Test
       • Changes to variables of a system
     • OBSERVATION
   • Product realization
     • Objective: "robust" process
   • Scientific method
     • Mechanistic models
   • Empirical models
   • General approach of planning and conducting an experiment
   • Best-guess Approach: Experiment over and over again, switching one or two factors
   • One-factor-at-a-time Approach
     • Consists on: Selecting a base-line set of leves and then varying each factor
       • Downside: fails to interact between factors
   • Factorial experiment
     • Best experiment for dealing with several factors
       • Why?
         • Because the factors are varied together, not one at a time
     • 2^2 Factorial Design
     • 2^3 Factorial Design
     • 2^4 Factorial Design

2. Typical Applications of Experimental Design

   • Caracterizing a Process
     • Used to determine which factors (controllable and uncontrollable) affect the process
       • Hecho por: Adrián Rumbaut, Patricio Morales y Darío Sanchez
   • Optimizing a Process
     • Used to determine the region in the important factors that leads to the best possible response
   • Designing a Product I
     • Used to specify a number of variables by designing parameters and prototypes
   • Designing a Product II
     • Used in experiments in which are impossible to create prototypes, instead they use computer models
   • Formulating a Product
     • Using a Mixture experiment, it is possible to combine various factors or ingredients

3. Basic Principles

   • Statistical design of experiments
     • Process of planning an experiment to analyze the appropriate data
   • Three Basic Principles
     • Randomization
       • Is the cornerstone underlying the use of statistical methods in experimental design
       • By randomizing an experiment, you "average out" the effects of extraneous factors
     • Replication
       • Independent repeat of each factor combination
     • Blocking