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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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ACF 75<br />

• If a natural log transformation is requested when there are values in the series that are less<br />

than or equal to zero, the ACF will not be produced for that series because nonpositive values<br />

cannot be log transformed.<br />

• NOLOG is generally used with an APPLY subcommand to turn off a previous LN specification.<br />

Example<br />

ACF SALES<br />

/LN.<br />

• This command transforms the series SALES using the natural log transformation and then<br />

computes and plots autocorrelations.<br />

SEASONAL Subcommand<br />

Use the SEASONAL subcommand to focus attention on the seasonal component by displaying<br />

and plotting autocorrelations only at periodic lags.<br />

• There are no additional specifications on SEASONAL.<br />

• If SEASONAL is specified, values are displayed and plotted at the periodic lags indicated<br />

on the PERIOD subcommand. If PERIOD is not specified, the periodicity established on<br />

the TSET or DATE command is used (see the PERIOD subcommand on p. 74).<br />

• If SEASONAL is not specified, autocorrelations for all lags up to the maximum are displayed<br />

and plotted.<br />

Example<br />

ACF SALES<br />

/SEASONAL<br />

/PERIOD=12.<br />

• In this example, autocorrelations are displayed only at every 12th lag.<br />

MXAUTO Subcommand<br />

MXAUTO specifies the maximum number of lags for a series.<br />

• The specification on MXAUTO must be a positive integer.<br />

• If MXAUTO is not specified, the default number of lags is the value set on TSET MXAUTO.<br />

If TSET MXAUTO is not specified, the default is 16.<br />

• The value on MXAUTO overrides the value set on TSET MXAUTO.<br />

Example<br />

ACF SALES<br />

/MXAUTO=14.<br />

• This command sets the maximum number of autocorrelations to be displayed for series<br />

SALES to 14.

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