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. If the numerator is
zero for a cell, that cell does not initiate suppression. This rule may
be set to be 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, the columns variable as sex and age group 15-24 is
specified.
AIDS Deaths in County A Age
15-24
Male
Female
Total
White
5
1
6
Black
3
1
4
Other
0
0
0
Total
8
2
10
The next table shows the same variables for total deaths.
Deaths in County A Age
15-24
Male
Female
Total
White
45
40
85
Black
9
12
21
Other
5
4
9
Total
59
56
115
Since the difference between total deaths and AIDS deaths to 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
tables 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.