PAPERBACK
\$59.00

• #### Committee on National Statistics 331-332

BOX 4-4

Illustrative Calculation for Suppressing Table Cells with Large Sampling Error, 1-Year ACS Period Estimates

Assume a city of population 100,000, with 2,000 school-age children in a particular population group (e.g., Hispanic).

First Pass of Table

 Ratio of Family Income to Poverty Threshold Percent Chldren in Category Coefficient of Variation (CV) Below poverty threshold 15.0 60.4 100–149 percent of poverty 10.0 76.1 150–199 percent of poverty 10.0 76.1 200–249 percent of poverty 10.0 76.1 250–299 percent of poverty 10.0 76.1 300–349 percent of poverty 20.0 50.7 350 percent or more of poverty 25.0 43.9

What is the result?

• Median CV is 76.1.

• The table may not be released because the median CV is greater than 61.0.

Second Pass of Table after Combining Categories

 Ratio of Family Income to Poverty Threshold Percent Chldren in Category Coefficient of Variation (CV) Below poverty threshold 15.0 60.4 100–199 percent of poverty 20.0 50.7 200–299 percent of poverty 20.0 50.7 300–349 percent of poverty 20.0 50.7 350 percent or more of poverty 25.0 43.9

What is the result?

• Median CV is 50.7.

• The table may be released because the median CV is less than 61.0.

Recommendation 4-10: The Census Bureau should monitor the extent of collapsing of cells that is performed in different tables to meet minimum precision standards of 1-year and 3-year period tabulations from the ACS and assess the implications for comparisons among geographic areas and over time. After sufficient information has been gleaned about the extent of data collapsing, the Census Bureau, in consultation with data users, should assess whether its collapsing rules are sound or should be modified for one or more subject areas.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001