• Component Description
• Eligible Sample
• Interview Setting and Mode of Administration
• Quality Assurance & Quality Control
• Data Processing and Editing
• Analytic Notes
• Codebook
  • SEQN - Respondent sequence number
  • VIQ030 - General condition of eyesight
  • VIQ040 - Time worrying about eyesight
  • VIQ050A - Difficulty reading ordinary newsprint
  • VIQ050B - Difficulty with up close work or chores
  • VIQ050C - Difficulty seeing steps/curbs-dim light
  • VIQ050D - Difficulty noticing objects to side
  • VIQ050E - Difficulty findng object on crowdedshelf
  • VIQ055 - Difficulty drivng daytime-familiar place
  • VIQ060 - Vision limits how long can do activities
  • VIQ070 - Ever had a cataract operation
  • VIQ080 - Operation in right, left or both eyes

National Health and Nutrition Examination Survey

2001-2002 Data Documentation, Codebook, and Frequencies

Vision (VIQ_B)

Data File: VIQ_B.xpt

First Published: February 2005

Last Revised: NA

Component Description

The vision section (abbreviated "VIQ" in the NHANES questionnaire variable naming convention scheme), provides personal interview data on several vision topics.

Topics and the target population groups in the VIQ section:

• General condition of eyesight (50+ yr)
• Time worrying about eyesight (50+ yr)
• Difficulty reading ordinary newsprint (50+ yr)
• Difficulty with up close work or chores (50+ yr)
• Difficulty seeing steps/curbs-dim light (50+ yr)
• Difficulty noticing objects to side (50+ yr)
• Difficulty finding object on crowded shelf (50+ yr)
• Difficulty driving daytime-familiar place (50+ yr)
• Vision limits how long can do activities (50+ yr)
• Ever had a cataract operation (50+ yr)
• If yes to cataract operation in right, left or both eyes (50+ yr)

Eligible Sample

Please review the questionnaire and codebook carefully. Frequency counts were verified during the preparation of the file.

Interview Setting and Mode of Administration

Trained household interviewers collected all of the Sample Person interviews. In most cases, the interview setting was the Sample Person's home. The information was recorded using a format computer-assisted personal interview (CAPI) system. All household interviewers were required to complete a comprehensive two-week training program. Many of the interviewers had prior interviewing experience. A large percentage of the household interviewers were bilingual in English and Spanish.

NHANES interviewer training included role-playing exercises and practice interviews, all of which were monitored by NCHS and contractor staff. Additionally, all of the NHANES questionnaires were translated into Spanish and were accessible in CAPI format. Detailed information about the interviewer training requirements is found in the NHANES Household Interviewer Training Manual.

Quality Assurance & Quality Control

Quality Control during Data Collection:

Several types of quality control were implemented to ensure that high quality data were collected during the survey.

Interviewer monitoring was a major responsibility for NCHS and contractor staff. Interviewers were frequently accompanied on interviews and observed to verify that the interview protocol was administered correctly. Interviewers were retrained on survey procedures if necessary.

Extensive pretesting was completed prior to implementing the questionnaires in the field. A full "dress rehearsal" pilot test was conducted with the field and examination staff to test all of the survey participant contact, interview, and examination procedures.

The interviewers are encouraged to provide comments and other suggestions, based on their field experiences. NCHS has used field staff and interviewer feedback to improve the questionnaires and survey materials. Annual staff debriefing and training sessions are conducted jointly by NCHS and contractor staff.

Interviewers are trained on new survey content and protocol changes prior to implementation in the field.
With respect to data collection quality control, the CAPI systems have built-in edit and range checks for most questions that have open-ended response options. When unusual or unrealistic responses were recorded, the interviewer is alerted immediately and instructed to verify or edit the initial response.

Data Collection:

All of the responses to the questionnaire items were recorded using the NHANES CAPI interview system. Some of the questions in the VIQ section required the use of printed hand cards. When necessary, the household interviewers read the hand card selections to the respondent.

Data Processing and Editing

Frequency counts were checked, "skip" patterns were verified, and the reasonableness of responses to the questions was reviewed.

There were no edits made to the responses to the questions.

Analytic Notes

The analysis of NHANES 2001–2002 vision data must be conducted with the key survey design and basic demographic variables. The NHANES 2001–2002 Household Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interviews. They also contain all survey design variables and sample weights for these age groups. Other household questionnaire and vision examination files may be linked to the vision questionnaire data file using the unique survey participant identifier SEQN.

Please refer to the NCHS analytic guidelines to determine the appropriate analytic plan for this dataset.

Codebook and Frequencies