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National Health Interview Survey

October 2015

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About NCHS

The National Center for Health Statistics (NCHS) is the nation’s principal health statistics agency, providing data to identify and address health issues. NCHS compiles statistical information to help guide public health and health policy decisions.

Collaborating with other public and private health partners, NCHS uses a variety of data collection mechanisms to obtain accurate information from multiple sources. This process provides a broad perspective on the population’s health, influences on health, and health outcomes.


National Health Interview Survey

The National Health Interview Survey (NHIS) provides information on the health of the U.S. civilian noninstitutionalized population through confidential interviews conducted in households. NHIS is one of the nation’s largest in-person household health surveys. It provides data for analyzing health trends and tracking progress toward achieving national health objectives.

These data, continuously collected throughout the year, are also used for epidemiological and policy analysis, such as characterizing those with various health conditions, determining barriers to accessing and using appropriate health care, and evaluating federal health programs.


Major Health Topics Addressed

  • Physical and mental health status
  • Chronic conditions, including asthma and diabetes
  • Access to and use of health care services
  • Health insurance coverage and type of coverage
  • Health-related behaviors, including smoking, alcohol use, and physical activity
  • Measures of functioning and activity limitations
  • Immunizations


Examples of NHIS Data

Health insurance

  • In 2014, a total of 36.0 million persons of all ages (11.5%) were uninsured at the time of the interview, 51.6 million (16.5%) had been uninsured for at least part of the year prior to the interview, and 26.3 million (8.4%) had been uninsured for more than a year at the time of the interview.
  • Among persons under age 65, 63.6% (170.4 million) were covered by private health insurance plans at the time of interview. This includes 2.2% (5.9 million) covered by private plans through the Health Insurance Marketplace or state-based exchanges at the time of interview between January and December 2014.
  • Among adults aged 18–64, the percentage who were uninsured at the time of interview decreased from 20.4% in 2013 to 16.3% in 2014.
  • In 2014, the percentage of persons under age 65 who were uninsured at the time of interview varied by state. For example, 2.5% were uninsured in Hawaii, whereas 21.5% were uninsured in Oklahoma and Texas.


 Figure 1 shows the heatlh insurance coverage status among persons under 65 years of age in the United States for 2014.

NOTE: Data are based on household interviews of a sample of the civilian noninstitutionalized population.
SOURCE: CDC/NCHS, National Health Interview Survey, 2014, Family Core component.


Physical activity

Current federal physical activity guidelines recommend that adults perform at least 150 minutes a week of moderate aerobic activity, 75 minutes a week of vigorous aerobic activity, or an equivalent combination of both. NHIS leisure-time physical activity data from 2014 show:

  • For both sexes combined, as age increased, the percentage of adults who met the 2008 physical activity guidelines for aerobic activity (based on leisure-time activity) decreased.
  • For adults aged 18 and over and within age groups 18–24, 25–64, 65–74, and 75 and over, women were less likely than men to meet the federal physical activity guidelines for aerobic activity (based on leisure-time activity).


 Figure 2 shows the percentage of adults who met the 2008 federal physical activity guidelines for leisure-time aerobic activity, by age group and sex in the United States for 2014.

SOURCE: CDC/NCHS, National Health Interview Survey, 2014.


Other NHIS data from 2014 show:

  • The percentage of persons of all ages with a usual place to go for medical care was highest for non-Hispanic white persons at 89.6% and lowest for Hispanic persons at 81.7%.
  • The percentage of current smokers among adults aged 18 and over was highest for non-Hispanic white persons at 19.2% and lowest for Hispanic persons at 10.5%.
  • The prevalence of diagnosed diabetes (based on self-report of a diagnosis by a doctor or other health professional) was higher among non-Hispanic black and Hispanic persons than among non-Hispanic white persons.


Wireless substitution data

Twice a year, NHIS releases the most up-to-date estimates of telephone coverage available from the federal government. These estimates, based on in-person interviews, are used by survey researchers and political pollsters to ensure that their random-digit-dial telephone surveys include sufficient numbers of households with only wireless telephones. If telephone surveys do not include wireless-only households, coverage bias could result from differences between persons with and without landline telephones for the substantive variables of interest.

  • Results show that nearly two of every five American homes (45.4%) had only wireless telephones during the second half of 2014, an increase of 4.4 percentage points since the second half of 2013. In addition, more than two-thirds of adults aged 25–29 lived in households with only wireless telephones (69.2%).
  • The percentage of adults who had at least one heavy drinking day in the past year was substantially higher among wireless-only adults (30.3%) than among adults living in landline households (19.6%).


Challenges and Future Opportunities

  • Implement an online system for real-time analysis of NHIS data, allowing users to easily analyze state-level data
  • Redesign the survey questionnaire to increase relevance, enhance data quality, and minimize respondent burden, in consultation with other federal agencies and the Healthy People program
  • Maintain efforts successful since 2005 to release public-use data files within 6 months of the data collection year


For further information about NCHS and its programs, visit
For further information about NHIS, visit