Select Structural Zeros

Click the Structural zeros button on the Log-Linear Model Specification dialog box - Advanced tab to display the Select Structural Zeros dialog box.

With Log-Linear Analysis, you can analyze incomplete tables, that is, tables containing structural zeros. Structural (as opposed to sampling) zeros are empty cells in the table that are empty by design. For example, suppose you tabulated the number of patients in a hospital by gender and diagnosis. If the hospital has a maternity ward, then the table will contain empty cells by design, namely, there will not be any males who are in the hospital to give birth.

Statistica finds all zero frequencies in the table and lists them in the Select Structural Zeros dialog box. You can then select the structural zeros from that list. Note that the correct computation of the degrees of freedom for models fit to tables with structural zeros can be extremely complex. Log-Linear will correctly compute the degrees of freedom for models involving structural zeros as long as those zero frequencies do not result in zeros in the marginal tables of the respective model.