# Data considerations for Define Custom 2-Level Factorial Design

Consider the following guidelines when you define the design.

The design should be to study 2-level factors
Text factors must have exactly two levels. To allow for center points, as well as botched runs, numeric factors can contain any number of numeric values. If you have more than two levels for a factor, not counting center points and botched runs, consider whether to define a general full factorial design or a response surface design instead.
The size of the design should be adequate
The sample size and power should be desirable for a practically important effect size. To evaluate a full or fractional 2-level design, use Stat > Power and Sample Size > 2-Level Factorial Design.
The center point column should contain only the values 0 and 1
To include a center point term in the model when you analyze the design, use these values in the center point column:
• 0: In rows for center points and pseudo-center points
• 1: In all other rows
The design should have 2 to 50 factors
If you have only one factor, you can use One-Way ANOVA without defining the design.
The run order should be randomized for data collection
If the worksheet contains a column that contains the run order, you can specify that column when you define the design. Otherwise, you can randomize the design after you define the design with Stat > DOE > Modify Design.