Survey description
The National Health Interview Survey
(NHIS) is a continuing nationwide survey of the U.S. civilian noninstitutionalized
population conducted in households. Each week a probability sample of households is
interviewed by trained personnel of the U.S. Bureau of the Census to obtain information
about the health and other characteristics of each living member of the sample household.
During a year, the sample is composed of 36,000 to 47,000 households, including 92,000 to
125,000 persons, depending upon the year. Information is obtained on the number of
restricted-activity days, bed days, work- or school-loss days, and all physician visits
occurring during the 2-week period prior to the week of the interview. Data are also
obtained on the acute and chronic conditions that were responsible for these days or
visits. Respondents are asked about long-term limitation of activity and the chronic
conditions related to this disability. All conditions are coded according to the Health
Interview Survey Medical Coding Manual and Short Index, a modified version of the
International Classification of Diseases, using the limited diagnostic detail available
from a household respondent. Data are obtained on all hospital episodes during the prior
12 months, including length of stay and whether surgery was performed.
Data file description
There are five possible record types, each containing data on a particular topic:
household characteristics, person characteristics, health conditions, doctor visits,
and hospital stays. Selected items from the person and household records are also included
on each of the other record types. The records are arranged in five files.
General list of variables by files
Household
Household ID number
Type of living quarters
Telephone in home
Interview type
Date of completion
Size of family
Region
Type of PSU
Type of MSA
Person Person ID number
Demographic variables
Sex
Age
Month and year of birth
Main racial background
Hispanic origin (1978-94 only)
Marital status
Veteran status
Education of:
Individual
Family head or
reference person
Family income
Family relationships
Family size
Born in the United States, number of years lived in
State of present
residence (1989-94 only)
Foreign-born, number of years lived in the United
States (1989-94
only)
Employment status
Class of worker
Industry
Occupation
Region
Respondent (self or proxy)
Height
Weight
Health and utilization
variables
Limitation of activity
Self-assessed health status (1972-95 only)
Restricted-activity days
Bed days
Work-loss days
School-loss days
Doctor visits
Hospital days
Bed days in 12 months (1977-95 only)
Doctor visits:
In the past 12
months
Interval since
last visit
Hospitalization:
Number of
episodes
Days in past 12
months
Condition
ID number
Same demographic variables as in Person Record
Conditions list assigned:
Musculoskeletal-skin
Impairments
Digestive
Miscellaneous
Circulatory
Respiratory
Condition codes
For all conditions:
Chronic or acute
code
Onset
Whether doctor seen
Last seen by
doctor
Related restricted-activity days:
Bed days
Work- or
school-loss days
Hospitalized
Condition status
Limitation of
activity due to chronic conditions:
Overall
limitation status
Limitation in
ability to work (1983-95 only)
Injuries:
Motor vehicle
involved
Place of
accident
Doctor visit
ID number
Same demographic variables as in Person Record
Date of visit
Place of visit
Type of doctor
Conditions causing visit
Operations performed (1982-95 only)
Hospital
ID number
Same demographic variables as in Person Record
Type of service
Hospital ownership
Date of admission
Date of discharge
Number of nights in hospital
Operation performed
Hospitalization for delivery (1984-95 only)
NOTES: MSA is metropolitan statistical
area. SMSA is standard metropolitan statistical area. ID is identification.
Data file technical characteristics The block size and record
length pertain to data stored on tape. The CD-ROM format comes with Statistical Export and
Tabulation System (SETS)
retrieval software.
Data
year
Record
length
Block
size
House-
hold
Person
Condi-
tion
Visits
Hospital
1996
360
32,760
25,990
63,402
44,357
14,024
6,103
1995
335
31,825
41,824
102,467
75,701
22,721
10,120
1994
335
31,825
48,584
116,179
89,199
27,811
11,811
1993
335
31,825
44,978
109,671
84,757
25,815
11,098
1992
335
3,350
51,643
128,412
97,630
29,215
13,111
1991
335
3,350
48,853
120,032
88,074
26,559
12,261
1990
335
3,350
48,860
119,631
92,534
25,312
12,524
1989
335
3,350
48,054
116,929
83,548
24,340
12,481
1988
335
3,350
50,061
122,310
88,345
25,541
13,580
1987
335
3,350
49,569
122,859
88,599
25,514
13,814
1986
335
3,350
24,698
62,052
45,106
12,833
7,074
1985
335
3,350
36,399
91,531
65,806
18,408
11,079
1984
335
3,350
41,471
105,290
75,260
20,515
13,515
1983
335
3,350
40,912
105,620
75,388
20,579
14,145
1982
335
3,350
39,988
103,923
72,340
20,505
14,022
1981
469
4,690
41,265
107,480
76,643
19,070
14,227
1980
480
4,800
39,226
102,629
74,182
18,764
13,863
1979
466
4,660
41,883
110,530
59,629
20,092
14,606
1978
516
5,160
41,164
109,940
57,517
20,100
14,583
1977
516
5,160
41,277
111,279
63,371
20,637
14,829
1976
480
4,800
41,559
113,178
58,346
21,550
15,239
1975
464
4,640
41,649
116,289
51,507
22,522
15,650
1974
478
4,780
41,314
116,287
37,453
15,692
22,058
1973
464
4,640
42,135
120,493
51,401
23,169
16,140
1972
464
4,640
46,149
132,891
63,714
100,245
17,553
1971
486
4,860
45,422
134,502
68,441
25,393
17,714
1970
516
5,160
39,011
116,466
68,331
21,412
16,073
1969
320
3,200
44,110
131,575
91,295
22,437
18,023
Geographic coverage Each person's region of
residence (four census categories) is shown. The SMSA is identified in data years
1969-84 if the sample person lived in one of the larger standard metropolitan statistical
areas (SMSAs) that was selected for the sample with certainty.
Data availability NHIS data are collected
annually. Data tapes
are available for individual years from 1969-96. Data on CD-ROM
are available from 1987-97. ASCII files for 1995-97 are available on CD-ROM directly
from from NCHS. The 1997 data
files and documentation are also available on the CDC/FTP Server.
An errata for the 1982-94 Condition files can be downloaded from the CDC/FTP
server.
In addition to the data files already
described, tapes containing data collected in special supplements (Current
Health Topics) to NHIS are available directly from the National Center for
Health Statistics. The CD-ROMs for 1987-97 contain most of the topics collected for each
data year. Data for the 1994 Income file can be downloaded from the CDC/FTP
Server.
NHIS State Data
files have been constructed to allow for the production of direct State
estimates.
Ordering information NHIS data tapes can only be
purchased through the National Technical Information Service (NTIS).
The CD-ROM can be purchased from NTIS and the Government Printing Office (GPO).
The NTIS and GPO order numbers are as follows:
Documentation content Each NHIS product contains
the necessary documentation, which includes tape content and technical information
needed to access the data. Data stored on tape is accompanied by printed documentation.
Documentation is available electronically on the CD-ROM. Documentation for the 1997
data file is available on the CDC/FTP
server.
Related reports A detailed description of
the survey and summary tables of the data are in the "Current Estimates" reports
of the Vital and Health Statistics, Series 10.
Data are also released in Advance Data
reports.
Contact
Division of Health Interview Statistics
National Center for Health Statistics
Centers for Disease Control and Prevention
3311 Toledo Road, Room 2217
Hyattsville, Maryland 20782-2003
(301) 458-4001