Income, Poverty, and Health Insurance Coverage ... - Census Bureau

Health Interview Survey (NHIS) data
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adjusting the CPS ASEC data. This is to compare and contrast CPS ASEC
instead of CPS data. The purpose of an experimental imputation, and was underreporting rates with other surthis
was two-fold: to provide expla- produced for interested parties to use veys. This, in turn, will allow Census
nations for the differences found in their research. The Census Bureau Bureau analysts to better understand
between NHIS data and MSIS files has not evaluated the methodology, the nature and impact of CPS ASEC
and to examine how differing survey and users should be aware that this is health coverage underreporting.
designs and methodologies affect the
survey data and estimates. The report
found that the NHIS Medicaid undercount
was 27.3 percent in 2001 and
21.7 percent in 2002, but noted that
the NHIS added questions in 2004 and
these results may not apply to more
recent data. The report found higher
false-negative reporting for enrollees
who were older, had higher incomes
and also had private insurance. False-
negative reporting was lower for very
low-income enrollees, those on other
benefits programs, and those who
had recently used Medicaid services.
The report found that the dynamics of
false-negative reporting was similar in
NHIS and CPS.
not an official data product.
There are several ongoing projects
aimed at improving the quality of
health coverage data from the CPS
ASEC. This research includes: 1)
cognitive research and field testing
to improve the wording of the CPS
ASEC health coverage questions;
2) editing and imputation research,
including additional research on the
use of models that attempt to account
for Medicaid underreporting; and 3)
expanding the number of studies that
match administrative Medicaid data to
current survey data to include other
surveys, such as the National Health
Interview Survey (NHIS) and the
American Community Survey (ACS).
After consulting with health insurance
experts, the Census Bureau modified
the definition of the population with-
out health insurance in the supplement
to the March 1998 CPS, which
collected data about coverage in
1997. Previously, people with no cov-
erage other than access to the Indian
Health Service were counted as part
of the insured population. Subsequently,
the Census Bureau has counted these
people as uninsured. In 2009, a modi-
fication to uninsured foster children
was made. Health insurance experts
informed the Census Bureau that
all foster children were eligible for
Medicaid. The effect of these changes
on the overall estimates of health
In November of 2008, SHADAC
released a new imputation adjustment
for public use CPS ASEC micro-
This research will make it possible insurance coverage was negligible.
data through their website to help
researchers interested in partially
3 See for more
information.
70 Income, Poverty, and Health Insurance Coverage in the United States: 2009 U.S. Census Bureau