SPSS® 12.0 Command Syntax Reference

1524 Syntax Reference
SPECTRA
Overview
Options
SPECTRA is available in the Trends option.
SPECTRA [VARIABLES=] series names
[/{CENTER NO**}]
{CENTER }
[/{CROSS NO**}]
{CROSS }
[/WINDOW={HAMMING** [({5 })] }]
{ {span} }
{BARTLETT [(span)] }
{PARZEN [(span)] }
{TUKEY [(span)] }
{UNIT or DANIELL [(span)]}
{NONE }
{w-p , ..., w0 , ..., wp }
[/PLOT= [P] [S] [CS] [QS] [PH] [A]
[G] [K] [ALL] [NONE]
[BY {FREQ }]]
{PERIOD}
[/SAVE = [FREQ (name)] [PER (name)] [SIN (name)]
[COS (name)] [P (name)] [S (name)]
[RC (name)] [IC (name)] [CS (name)]
[QS (name)] [PH (name)] [A (name)]
[G (name)] [K (name)]]
[/APPLY [=’model name’]]
**Default if the subcommand is omitted.
Example:
SPECTRA HSTARTS
/CENTER
/PLOT P S BY FREQ.
SPECTRA plots the periodogram and spectral density function estimates for one or more series.
You can also request bivariate spectral analysis. Moving averages, termed windows, can
be used for smoothing the periodogram values to produce spectral densities.
Output. In addition to the periodogram, you can produce a plot of the estimated spectral density
with the PLOT subcommand. You can suppress the display of the plot by frequency or
the plot by period using the keyword BY on PLOT. To display intermediate values and the plot
legend, specify TSET PRINT=DETAILED before SPECTRA. To reduce the range of values displayed
in the plots, you can center the data using the CENTER subcommand.