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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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538 <strong>Syntax</strong> <strong>Reference</strong><br />

VARIABLES Subcommand<br />

MODEL Subcommand<br />

VARIABLES specifies the series names and is the only required subcommand. The actual keyword<br />

VARIABLES can be omitted.<br />

• For seasonal models, the series must contain at least four full seasons of data.<br />

MODEL specifies the type of model to be used.<br />

• The only specification on MODEL is a model keyword.<br />

• Only one model keyword can be specified. If more than one is specified, only the first is<br />

used.<br />

The following models are available. Table 1 summarizes the models by trend and seasonal<br />

component.<br />

No trend models:<br />

NN No trend and no seasonality. This is the default model. The keyword SINGLE is an<br />

alias for NN.<br />

NA No trend and an additive seasonal component.<br />

NM No trend and a multiplicative seasonal component.<br />

Linear trend models:<br />

LN Linear trend component and no seasonality. The keyword HOLT is an alias for LN.<br />

LA Linear trend component and an additive seasonal component.<br />

LM Linear trend component and a multiplicative seasonal component. The keyword<br />

WINTERS is an alias for LM.<br />

Exponential trend models:<br />

EN Exponential trend component and no seasonality.<br />

EA Exponential trend component and an additive seasonal component.<br />

EM Exponential trend component and a multiplicative seasonal component.<br />

Damped trend models:<br />

DN Damped trend component and no seasonality.<br />

DA Damped trend component and an additive seasonal component.<br />

DM Damped trend component and a multiplicative seasonal component.

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