Major changes in data collection technology
- From 1957 through 1996, the NHIS was printed as a paper questionnaire. The interviewer read the questions and marked boxes or wrote verbatim responses in the questionnaire document. Results pertaining to injuries were subsequently read by a medical coder who identified an ICD code for the injury and subsequently keyed selected data fields and the ICD code(s) into a computer in preparation for data processing.
- From 1997 through 2003, the NHIS used CASES software for computer-assisted personal interviewing (CAPI). The interviewer read the questions from the screen of a laptop computer and entered the responses directly into the computer.
- In 2004, the NHIS questionnaire converted from CASES to BLAISE CAPI software. This technology continues to the present.
Major changes in injury and poisoning questions
- Beginning with the first survey in 1957, questions on accidents and injuries were included in the core questionnaire each year, and, in some years, these questions were expanded into both minor and substantial supplements to the NHIS core. There were no questions asked specifically about poisoning, although injury caused/inflicted by a poisonous substance swallowed with the substance specified was included as a response category.
- In 1997, a redesigned NHIS questionnaire was fielded that contained a section devoted entirely to injuries and poisonings. The Family Core Injury Section (FIJ) asked detailed questions about medically attended injuries and poisonings that occurred to any member of the family within the previous three-month reference period.