About This Early Release

Early Release of Selected Estimates Based on Data From the January-September 2002 National Health Interview Survey

In this release, the National Center for Health Statistics (NCHS) provides updated estimates for 13 selected health measures based on new data from the January-September 2002 National Health Interview Survey (NHIS), with comparisons to estimates from the NHIS back to 1997. The 13 Early Release measures are being published prior to final data editing and final weighting to provide access to the most recent information from the NHIS.

The 13 measures included are health insurance coverage (including lack of health insurance and type of coverage), usual place to go for medical care, obtaining needed medical care, influenza vaccination, pneumococcal vaccination, obesity, leisure-time physical activity, current smoking, alcohol consumption, HIV testing, general health status, personal care needs, and serious psychological distress.

For each selected health measure, a graph is presented showing the trend over time from 1997 through September 2002 for the total population, followed by graphs and tables showing estimates by sex, age group, and race/ethnicity (Hispanic or Latino, white non-Hispanic, and black or African America non-Hispanic) based on data from the January-September 2002 NHIS. Key findings are highlighted with bulleted text. Data tables providing values displayed in the graphs are included at the end of each section. This release also provides updates for age-adjusted estimates for those early release measures that are also Healthy People 2010 leading health indicators (lack of health insurance, usual place to go for medical care, influenza vaccination, pneumococcal vaccination, obesity, leisure-time physical activity, and current smoking)(1). In this release, the terms "Hispanic'' and "Black'' have been changed to "Hispanic or Latino'' and "Black or African American,'' although the definitions of the categories have remained unchanged. These changes have been made based on the new standards for the classification of Federal data on race and ethnicity(2).

Data source

The data are derived from the following three components of the 2002 NHIS (January-September): the Family Core questionnaire, which collects information on all family members (data for 70,768 persons); the Sample Adult Core questionnaire, which collects information from one randomly selected adult aged 18 years or over in each family in the NHIS (data for 23,577 adults); and the Sample Child Core questionnaire, which collects information about one randomly selected child in each family with a child in the NHIS (data for 9,502 children). Visit the NHIS Web site for more information on the design, content, and use of the NHIS.

Estimation procedures

Using population totals provided by the U.S. Bureau of the Census, sample weights were calculated to provide national estimates for the noninstitutionalized civilian population and to adjust for nonresponse. NCHS creates weights for each calendar quarter of the NHIS sample. The NHIS data weighting procedure has been described in more detail elsewhere (Design and Estimation for the National Health Interview Survey, 1995–2004 [PDF - 300 KB]). Because the estimates for the year 2002 are being released prior to final data editing and final weighting, they should be considered preliminary and may differ slightly from estimates made later using the final data files. Except for health insurance coverage, estimates from the 1997-2001 NHIS were derived from the final data files for those years. See health insurance coverage section for details. For the NHIS announcements and more detailed information, check the NHIS Web site .

Point estimates and estimates of their variances were calculated using the SUDAAN software package to account for the complex sample design of the NHIS. The Taylor series linearization method was chosen for variance estimation. All estimates shown meet the NCHS standard of having less than 30% relative standard error. Point estimates in some figures are shown with 95% confidence intervals. Differences between percents or rates were evaluated using two-sided significance tests at the 0.05 level. Terms such as "greater than" and "less than" indicate a statistically significant difference. Terms such as "similar" and "no difference" indicate that the statistics being compared were not significantly different. Lack of comments regarding the difference between any two statistics does not necessarily mean that the difference was tested and found to be not significant. When appropriate for comparison purposes, direct standardization was used to calculate age-sex-adjusted or age-adjusted percents using the 2000 U.S. standard population. The age groups used varied depending upon the impact of age on specific measures. Rates presented are crude rates unless otherwise stated.

Future plans for early release of NHIS estimates

The NCHS Early Release Program will update and release estimates 6 months after NHIS data collection has been completed for each quarter. These releases are tentatively scheduled for March, June, September, and December. New measures may be added as work continues and in response to changing data needs. Feedback on the Early Release mechanism and on the estimates is welcome (e-mail). Announcements about Early Releases, other new data releases, publications, or corrections related to the National Health Interview Survey (NHIS) will be sent to members of the HISUSERS Listserv. To join, visit the NCHS Listservs page.