# Overview for Create Definitive Screening Design

Use Create Definitive Screening Design to create a designed experiment to identify the most important factors early in the experimentation process. Definitive screening designs can fit 2–48 factors. Categorical factors can have only 2 levels. Continuous factors have 3 levels in the designs. Usually, you use a definitive screening design when you are starting with 6 or more factors and want to identify the most critical factors to study in subsequent experiments. Definitive screening is useful when you want to consider both linear and quadratic terms when you identify the most critical factors.

When you create a design, Minitab stores the design information in the worksheet, which shows the order in which data should be collected. Once you have collected your data, use Analyze Screening Design to analyze the data.

For example, process engineers design an experiment to study various factors that affect the output power for a new ultrasonic cleaner. The experiment includes 7 factors. The engineers create a definitive screening design so that they can determine which factors are most important. Then, the engineers plan to use a different design to study these factors in greater detail.

This Minitab worksheet shows a portion of the definitive screening design. The engineers perform the experiment by collecting data using the order shown in the RunOrder column, which contains the randomized order fo the runs.

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11
StdOrder RunOrder PtType Blocks Train Degas Burst Quiet Center Bandwidth Sweep
3 1 2 1 0.10 0.10 10.0 10.0 10 5 0
4 2 2 1 1.00 0.10 1.0 10.0 5 10 0
11 3 2 1 0.10 0.55 1.0 10.0 0 10 10
10 4 2 1 0.55 0.10 1.0 1.0 0 0 0
1 5 0 1 0.55 0.55 5.5 5.5 5 5 5
6 6 2 1 0.10 0.10 1.0 5.5 10 0 10
12 7 2 1 1.00 1.00 10.0 5.5 0 10 0

After collecting the data, an engineer enters the response data in an empty column in the worksheet and then analyzes the design.

Many of the choices you make when you create a design depend on your overall experimental plan. For more information, go to Phases of a designed experiment.

## Where to find this analysis

Stat > DOE > Screening > Create Screening Design

## When to use an alternate analysis

• If you already have factor columns in a worksheet, use Define Custom Screening Design. Custom designs let you specify which columns are the factors and any other design columns that you already have.