There are two confidentiality rules (and their respective settings) in MICA.
The first confidentiality rule affects suppression of the display of the entire inner table (i.e., the individual cells) of a report. This occurs when the difference between any particular cell and the total number of events for all conditions is less than 10 (less than 2 in the WIC MICAs). If the numerator is zero for a cell, that cell does not initiate suppression. This rule may be set to either on or off for the entire dataset and affects all variables in the dataset. It does not affect the display of row or column totals.
The following example shows a table for AIDs deaths in county A, with the row variable as race and the column variable as sex. Age group 15-24 is specified as an optional variable.
The next table shows the same variables for total deaths.
Since the difference between total deaths and AIDS deaths for black males is 6 (9-3), the confidentiality rule is invoked and the inner table is suppressed. The small numbers in the other cells of the AIDS death table do not invoke suppression because there are a sufficient number of total deaths with similar characteristics to protect the identity of the persons with AIDS.
The second confidentiality rule is not enabled unless the first confidentiality rule is enabled. If any row or any column has only one number not zero, then that row or column is suppressed.