Fourier (Spectral) Analysis

Click the Spectral (Fourier) analysis button in the Time Series Analysis Startup Panel to display the Fourier (Spectral) Analysis dialog box, which contains four tabs: Quick, Advanced, Autocorrelations, and Review series.

Use the Fourier (Spectral) Analysis dialog box to perform Spectrum (Fourier) Analysis for single variables as well as Cross-spectrum Analysis (see also, Time Series Analysis Index).

Element Name Description
OK (Single series Fourier analysis) Click the OK (Single series Fourier analysis) button to display the Fourier (Spectral) Analysis Results dialog box.

It is expected that you first highlighted a variable to be analyzed (click in the Variable or Long variable (series) name column to highlight the variable (series) in the active work area, see below). For cross-spectrum analysis, that variable will be treated as the x or independent variable. Then select the desired options (using the Quick tab, Advanced tab, Autocorrelations tab, and/or the Review series tab), and then click the OK (Single series Fourier analysis) button to begin the analysis and display the Fourier (Spectral) Analysis Results dialog box. Note that the input series should contain an even number of valid observations. If this is not the case, then the last case of the series will automatically be ignored.

Note: new (e.g., transformed) variables are appended to the active work area. Thus, make sure that there is sufficient space in the active work area. Increase the Number of backups parameter if necessary. Also, be sure to Lock all important backups of the original variable (those you want to retain); otherwise, those backups can be overwritten.
Active work area The Active work area is composed of three columns: Lock, Variable, and Long variable (series) name. For detailed information on the Active work area, see Time Series Analysis - Active Work Area.
Lock Double-click on a transformed variable in the Lock column to lock or unlock the variable in the active work area. An L is listed in the column to indicate that the variable is locked. Locked variables will not be replaced as successive transformations exceed the current maximum number of backups. Note that original (untransformed) variables are always locked, and they cannot be unlocked. For more information, see Active Work Area.
Variable The Variable column contains the short name of the variable(s) currently available for analysis. Click on a variable name in the list to highlight that variable (series) in the Active work area that is to be analyzed For more information, see Active Work Area.
Long variable (series) name When a new (e.g., transformed) variable is appended to the active work area, the Long variables (series) name column will display a new long variable name that consists of the old long variable name (as much of it as will fit) and a brief description of the respective transformation that was performed. For more information, see Active Work Area.
Number of backups per variable (series) The parameter entered in the Number of backups per variable (series) box determines the maximum number of backups (i.e., previous versions of the series) that is kept in the active work area for each variable. After a transformation (or other analysis) is performed on a series, the resulting transformed series (or residuals, forecasts, etc.) will be appended to the active work area, and the values of the series prior to the transformation will be maintained as a backup. When a new transformation is appended and the maximum number of backups for the respective original variable is exceeded, the "oldest" previous backup will be replaced. You can lock a variable (prevent it from being overwritten) by double-clicking on the respective variable in the Lock column. For more details, refer to Active Work Area.
Save variables Click the Save variables button to save the variables (series) in the Active work area into a standard STATISTICA data file. You can save all variables or only selected variables.
Delete Click the Delete button to delete a highlighted transformed variable from the Active work area. Original (untransformed) variables cannot be deleted.
Cancel Click the Cancel button to return to the Time Series Analysis Startup Panel.
Options Click the Options button to display the Options menu.