NHANES I was conducted from 1971-1975. Population subgroups considered to be at high risk of malnutrition were oversampled. Approximately 32,000 persons ages 1-74 years old were interviewed and 23,808 received a medical examination. The majority of survey components were completed by June of 1974.
However, a subsample of 3,854 individuals was selected to receive a detailed medical examination component. The detailed medical examination component was extended past the June 1974 date until October 1975, in order to reach a total detailed sample of just over 6,900 persons. The detailed subsample represents the civilian, non-institutionalized population of the United States aged 25-74 years at the midpoint of the survey, without any oversampling. Other specialized subsamples are also available for analyses, however most analysts will require either major components utilizing data from the main sample taken from stands 1-65, or the detailed medical examination data from all stands 1-100, or both. The other subsample categories are rarely used.
NHANES I data were originally released in a series of separate data tapes, and are currently available as ASCII files on the NHANES website. All the data tapes contained demographic information such as age, gender, race, income, occupation and education. The household adult file contains survey design variables, such as weights, strata and primary sampling units, and demographic variables. In addition, it contains data collected through the household adult questionnaire administered to survey participants aged 17 years and older during the household interview. Each tape thereafter focused on a particular component of the survey, according to the method of data collection.
The categories listed below represent data collected from the general survey and medical examination.
For the detailed medical examination subsample, in addition to the information collected above, the following data file releases are also available (along with additional laboratory determinations).
IMPORTANT NOTETypically, most analysts will extract data from several of these data files and merge them into one data file to do their analyses. All analysts should be aware that the demographic information, while standard to each tape, is only provided for the actual persons who participated in that component. This means that when you choose to merge different tapes, you should be careful to extract your demographic variables from the tape with the largest number of records.
Several of the data files are very large, and variables tend to be grouped as they were in the questionnaires. Care should be taken to search multiple data files, as some items of interest, such as aspirin use, were ascertained on both the general population and the detailed subsample (e.g. biochemistry and arthritis data files). For more information on how to search NHANES I data file documentation, please see the Locate Variables module.
In the animated explanation, linked below, click the headings to see examples of the types of data to be found in some of the various data files constituting the NHANES I data releases. Or, review the table below see examples of the types of data to be found in some of the various data files constituting the NHANES I data releases.
View an animated explanation of the component descriptions.
| File No. | Abbr | Title | Sample Size | Stands | Contents | Comments |
|---|---|---|---|---|---|---|
| 4111 |
BM |
Anthropometry Goniometry, Skeletal Age, Bone Density,
and Cortical Thickness, Ages 1-74 years |
23,808 |
1-35 1-65 1-100 |
Height and weight, body and skin-fold measurements for all examinees. Some data imputed. |
Some data collected only on detailed examinees. X-rays of the hand and wrist were taken of examinees 1-17 years of age. |