User Guide

117

Categorical Variable Coding Schemes

Each row except the means row sums to 0. Products of each pair of disjoint rows sum

to 0 as well:

The special contrasts need not be orthogonal. However, they must not be linear

combinations of each other. If they are, the procedure reports the linear dependency

and ceases processing. Helmert, difference, and polynomial contrasts are all

orthogonal contrasts.

Indicator

Indicator variable coding. Also known as dummy coding, this is not available in

LOGLINEAR or MANOVA. The number of new variables coded is . Cases in the

reference category are coded 0 for all variables. A case in the ith category is

coded 0 for all indicator variables except the ith, which is coded 1.

Rows 2 an

3: 3()0() 1–()2() 1–()1–() 1–()1–()+++0=

Rows 2 and 4: 3()0() 1–()0() 1–()1() 1–()1–()+++ 0=

Rows 3 and 4: 0()0() 2()0() 1–()1() 1–()1–()++ + 0=

k 1–