GLM Syntax - Example 5: 2(k-p) Fractional Factorial

This example illustrates the specification for a fractional factorial 2(7-4) design. Use the example data file Cycling.sta. Note that a single two-way interaction (Tires*Breakfst) was added into the Design statement, even though only main effects can be estimated; the use of SSTYPE=5 will automatically delete all redundant higher order effects from the model (see Type V sums of squares for details). Further details concerning this data set and the analysis are also discussed in the context of the Experimental Design module (see Designing and Analyzing a 2**(7-4) Fractional Factorial Design).  

GLM;

{ Dependent variable: }

   DEPENDENT = TIME;

{ Specification of grouping variables (factors); note that

   in this example, the numeric values (codes) are specified that

   identify each group; these values are optional, and if left out,

   the program would by default use all values (codes) found in the

   data file. }

   GROUPS = SEAT    (1 -1)

            DYNAMO  (1 -1)

            HANDLBRS(1 -1)

            GEAR    (1 -1)

            RAINCOAT(1 -1)

            BREAKFST(1 -1)

            TIRES   (1 -1);

{ A main-effects design is specified, with one additional  interaction term. }

   DESIGN = SEAT+DYNAMO+HANDLBRS+GEAR+

            RAINCOAT+BREAKFST+TIRES+

            TIRES*BREAKFST;

{ Type V sums of squares are requested:  In the final model, for all effects

  which are included in the model, all least squares means are estimable.  

  See Type V sums of squares for additional details. }

   SSTYPE = 5;

For more examples, see GLM Syntax Examples.

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