SAVE Subcommand (SPECTRA command)

SAVE saves computed SPECTRA variables to the active dataset for later use. SPECTRA displays a list of the new variables and their labels, showing the type and source of those variables.

  • You can specify any or all of the output keywords listed below.
  • A name to be used for generating variable names must follow each output keyword. The name must be enclosed in parentheses.
  • For each output keyword, one variable is created for each series named on SPECTRA and for each bivariate pair.
  • The keywords RC, IC, CS, QS, PH, A, G, and K apply only to bivariate analyses. If CROSS is not specified, these keywords are ignored.
  • SAVE specifications are not used when models are reapplied by using APPLY. They must be specified each time variables are to be saved.
  • The output variables correspond to the Fourier frequencies. They do not correspond to the original series.
  • Because each output variable has only (n/2 + 1) cases (where n is the number of cases), the values for the second half of the series are set to system-missing.
  • Variable names are generated by adding _n to the specified name, where n ranges from 1 to the number of series specified.
  • For bivariate variables, the suffix is _n_n, where the ns indicate the two variables that are used in the analysis.
  • The frequency (FREQ) and period (PER) variable names are constant across all series and do not have a numeric suffix.
  • If the generated variable name is longer than the maximum variable name length, or if the specified name already exists, the variable is not saved.

The following output keywords are available:

FREQ . Fourier frequencies.

PER. Fourier periods.

SIN. Value of a sine function at the Fourier frequencies.

COS. Value of a cosine function at the Fourier frequencies.

P. Periodogram values.

S. Spectral density estimate values.

RC. Real part values of the cross-periodogram. Applies only to bivariate analyses.

IC. Imaginary part values of the cross-periodogram. Applies only to bivariate analyses.

CS. Cospectral density estimate values. Applies only to bivariate analyses.

QS. Quadrature spectrum estimate values. Applies only to bivariate analyses.

PH. Phase spectrum estimate values. Applies only to bivariate analyses.

A. Cross-amplitude values. Applies only to bivariate analyses.

G. Gain values. Applies only to bivariate analyses.

K. Squared coherency values. Applies only to bivariate analyses.

Example

SPECTRA VARIABLES=STRIKES RUNS
   /SAVE= FREQ (FREQ) P (PGRAM) S (SPEC).
  • This example creates five variables: FREQ, PGRAM_1, PGRAM_2, SPEC_1, and SPEC_2.