# Define Method of Factor Extraction

Principal Components and Factor Analysis

Select an Input file and Variable(s) via the Factor Analysis Startup Panel - Quick tab and click the OK button in the Factor Analysis Startup Panel to display the Define Method of Factor Extraction dialog box, which contains three tabs: Quick, Advanced, and. Use the options in this dialog box to determine 1) the manner in which factors are extracted and 2) how many factors will be extracted. Both issues are discussed in greater detail in the Introductory Overviews. Use the Quick tab to quickly specify a model for factor analysis; use the Advanced and Descriptives tabs to access more detailed options for your analysis.

Summary box. The Summary box at the top of the dialog box displays a general summary of the current analysis.

Copy button. Click the Copy button to copy either the selected text (if text has been selected) in the Summary box or all of the text (if no text has been selected) to the Clipboard. Note that the copied text retains formatting information (such as font, color, etc.).

Contract/Expand button. Click the Contract/Expand button to contract or expand the Summary box. When contracted, you can see only one line of the Summary box text and can scroll through the text using a scroll bar. Note that when contracted the text is scrolled so that the first non-blank line is at the top. When expanded (the default setting), the entire Summary box will be displayed on the Define Method of Factor Extraction dialog.

OK. Click the OK button to display the Factor Analysis Results dialog box.

Cancel. Click the Cancel button to return to the Factor Analysis Startup Panel.

Options. Click the Options button to display the Options menu.

Note: matrix ill-conditioning and the modified correlation matrix. The Introductory Overviews discuss the issue of matrix ill-conditioning. If during the factoring process a message is displayed that the correlation matrix cannot be inverted, then, the correlation matrix will be modified (to allow inversion). Specifically, a small constant is added to the diagonal of the correlation matrix until the determinant of that matrix is greater than 1.e-50. All subsequent computations will be performed based on the modified (slightly lowered) correlations; to restore the original exact correlation matrix, click the Cancel button to return to the Factor Analysis Startup Panel, and then click the OK button to reread the data file.