purposes of the data collection activities. How to approach this challenge is a major focus of the committee's recommendations on ways to improve the state of the art of access monitoring.
Vital statistics are derived from birth and death certificates. The birth certificate is the major source of information about the use of prenatal care and low birthweight. In general, physician records about a woman's visits during pregnancy are transferred to the hospital for inclusion on the certificate. However, information on a birth record about the content of prenatal visits is limited. Data problems arise either when women have no or multiple providers or when recall of service use is required after delivery. Thus, threats to the validity of the data come from those most likely to have poor pregnancy outcomes—the poor, the young, minorities, noncitizens illegally residing in the United States, and the poorly educated.
Death records provide mortality statistics and when linked to the birth record offer insight into the important correlates of infant mortality related to prenatal care. The cause-of-death information recorded on a death certificate can be used to compare the mortality experience of different subpopulations and to assess its relationship to access barriers. Concerns have been expressed about the accuracy of cause-of-death information because it is based on the judgment of the certifying physician.
For the purposes of monitoring access for all age groups, the major limitation of the death certificate is its lack of relevant information on the possible extent of access barriers as a result of lack of insurance, low-income, or other such impediments. This limitation can be overcome in part through special followback surveys of a patient's closest relative.
Large household surveys such as the National Health Interview Survey (NHIS) provide a wealth of information that allows analysts to relate the use of health services and self-reports of health status to characteristics of individuals and families. Key strengths of the NHIS are its periodicity (it is conducted annually), its large and carefully constructed sample (about 120,000 respondents), and its well-tested questionnaire items.
Like most health care surveys, the NHIS suffers from its reliance on respondents' recall of when and how most services were used and the imprecision of self-reports of health status when compared with health examination data or medical record abstracts. The NHIS has questionnaire items