Log-Linear Analysis of Frequency Tables

Click the OK button in the Log-Linear Model Specification dialog box to display the Log-Linear Analysis Results dialog box, which contains three tabs: Quick, Advanced and More fit statistics.

Note that the observed and marginal frequency tables that can be displayed from this dialog box will include the Delta constant, as specified on the Log-Linear Model Specification dialog box - Advanced tab. Therefore, when using Log-Linear as a crosstabulation program, make sure that Delta is set to 0 (zero); otherwise you will not obtain accurate frequency counts.

A particularly useful Graph of Input Data for all tables is the 3D histogram. This graph is very helpful in order to visualize the pattern of frequencies, residuals, etc. in the table.

Summary Box. The Summary box at the top of the dialog box displays information about the current log-linear 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 scrollbar. 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 Results dialog box.

Summary. Click the Summary button to create a spreadsheet containing the Maximum Likelihood Chi-square value and the Pearson Chi-square value, along with their corresponding degrees of freedom and p-values.

Cancel. Click the Cancel button to return to the Log-Linear Model Specification dialog box.

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

Note: Plot options. After selecting any of the plot options, a scatterplot of the respective values will be displayed:

1. A plot of the observed versus fitted (expected) frequencies;

2. A plot of the fitted frequencies versus residual frequencies (observed minus fitted);

3. A plot of fitted frequencies versus standardized residuals;

4. A plot of fitted frequencies versus components of the maximum likelihood ratio Chi-square;

5. A plot of the fitted frequencies versus Freeman-Tukey deviates.

These graphs are very useful for evaluating the overall fit of the model for different magnitudes of frequencies, and for detecting outliers.