Specifying a model
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Specify a model in the Model text box using the form Y = expression. The Y is not included in the Model text box. The Calc > Make Patterned Data > Simple Set of Numbers command can be helpful in entering the level numbers of a factor.

Rules for Expression Models

1    * indicates an interaction term. For example, A*B is the interaction of the factors A and B.

2    ( ) indicate nesting. When B is nested within A, type B(A). When C is nested within both A and B, type C(A B). Terms in parentheses are always factors in the model and are listed with blanks between them.

3    Abbreviate a model using a | or ! to indicate crossed factors and a - to remove terms.

Models with many terms take a long time to compute.

Examples of what to type in the Model text box

Two factors crossed: A B A*B

Three factors crossed: A B C A*B A*C B*C A*B*C

Three factors nested: A B(A) C(A B)

Crossed and nested (B nested within A, and both crossed with C): A B(A) C A*C C*B(A)

    When a term contains both crossing and nesting, put the * (or crossed factor) first, as in C*B(A), not B(A)*C

Example of entering level numbers for a data set

Here is an easy way to enter the level numbers for a three-way crossed design with a, b, and c levels of factors A, B, C, with n observations per cell:

1    Choose Calc > Make Patterned Data > Simple Set of Numbers, and press <F3> to reset defaults. Enter A in Store patterned data in. Enter 1 in From first value. Enter the number of levels in A in To last value. Enter the product of bcn in Number of times to list the sequence. Click OK.

2    Choose Calc > Make Patterned Data > Simple Set of Numbers, and press <F3> to reset defaults. Enter B in Store patterned data in. Enter 1 in From first value. Enter the number of levels in B in To last value. Enter the number of levels in A in Number of times to list each value. Enter the product of cn in Number of times to list the sequence. Click OK.

3    Choose Calc > Make Patterned Data > Simple Set of Numbers, and press <F3> to reset defaults. Enter C in Store patterned data in. Enter 1 in From first value. Enter the number of levels in C in To last value. Enter the product of ab in Number of times to list each value. Enter the sample size n in Number of times to list the sequence. Click OK.