SPSS® 12.0 Command Syntax Reference

1526 Syntax Reference
Syntax Rules
Operations
Limitations
Example
• VARIABLES can be specified only once.
• Other subcommands can be specified more than once, but only the last specification of
each one is executed.
• SPECTRA cannot process series with missing observations. (You can use the RMV command
to replace missing values, and USE to ignore missing observations at the beginning
or end of a series. See RMV and USE in the SPSS Syntax Reference Guide for more information.)
• If the number of observations in the series is odd, the first case is ignored.
• If the SAVE subcommand is specified, new variables are created for each series specified.
For bivariate analyses, new variables are created for each series pair.
• SPECTRA requires memory both to compute variables and to build plots. Requesting fewer
plots may enable you to analyze larger series.
• Maximum 1 VARIABLES subcommand. There is no limit on the number of series named
on the list.
SPECTRA HSTARTS
/CENTER
/PLOT P S BY FREQ.
• This example produces a plot of the periodogram and spectral density estimate for series
HSTARTS.
• CENTER adjusts the series to have a mean of 0.
• PLOT specifies that the periodogram (P) and the spectral density estimate (S) should be
plotted against frequency (BY FREQ).
VARIABLES Subcommand
VARIABLES specifies the series names and is the only required subcommand. The actual keyword
VARIABLES can be omitted.
• VARIABLES must be specified before the other subcommands.
• Each series specified is analyzed separately unless the CROSS subcommand is specified.
• The series must contain at least six cases.