These rules were approved by the Disclosure Review Board (DRB) on January 29,
2004. They will continue to be scrutinized and possibly changed as the DRB
reviews more requests for special tabulations.
All Census 2000 special tabulations must be reviewed by the Disclosure
All cells in any Census 2000 special tabulation must be rounded. The
rounding schematic for most tables is:
0 remains 0
1-7 rounds to 4
8 or greater rounds to nearest multiple of 5 (i.e., 864 rounds to 865,
982 rounds to 980)
Any number that already ends in 5 or 0 stays as is.
In some circumstances, Census 2000 special tabulations must be rounded to
10’s. In particular, any special tabulations presenting data on the
population in households or the population in group quarters must be rounded
to 10’s. These data could be found in the universe of a table, presented
as a variable, or obtained by subtraction when comparing datasets (e.g.,
comparing the variables and universes of the special tabulation with those
in Summary File 3).
The exact rounding scheme for rounding to 10’s is:
0 remains 0
1-4 rounds to 0
5-14 rounds to 10
15-24 rounds to 20, etc.
This rounding to the nearest 10 also applies to those special tabulations
pertaining to poverty status and disability where there is a possibility of
obtaining group quarters or household data by subtraction.
This rounding applies to all special tabulations that pertain
to the population in households or the population in group quarters -- those
done under reimbursable agreement, those done for working papers, tables,
professional papers, etc. Examples of tabulations that must be rounded to
10’s can be obtained from the Decennial Programs Coordination Branch
of the Population Division (301-763-2429).
Any totals or subtotals needed should be constructed before rounding. This
assures that universes remain the same from table to table, and it is
recognized that cells in a table will no longer be additive after rounding.
Medians or other quantiles may be calculated as
an interpolation from a frequency distribution of unrounded data (these
are not subject to additional rounding), or
as a point quantile. These must be rounded to two significant digits:
12,345 would round to 12,000; 167,452 would round to 170,000. There must
be at least 5 cases on either side of the quantile point. It is recognized
that the interpolated quantile may indeed be some individual’s
response, but it is coincidental, not by design.
Thresholds on universes will normally be applied to avoid showing data for
very small geographic areas or for very small population groups (often 50
unweighted cases for sample data). Tables may normally not have more than 3
or 4 dimensions, and mean cell size lower limits may also be required (mean
cell size of each table is 3 for 100% data, or 20 weighted for sample data).
Percents, rates, etc., should be calculated after rounding, but the DRB
has granted exceptions to this rule when the numerator and/or denominator of
the percent or rate is not shown.
Means and aggregates must be based on at least 3 values.
The finest level of detail shown for Groups Quarters data will be
For Demographic Profiles from user-defined geographic areas (neighborhoods),
all areas must have at least 300 people in them. Using a computer program,
the user-defined areas will be compared with standard Census Bureau areas to
make sure users cannot obtain data from very small geographic areas by
subtraction. If such small areas are found, the boundaries of the user-defined
areas must be changed.
Source: U.S. Census Bureau, Population Division Questions? / 1-866-758-1060