Citation: Zeni, N.B. (June 30, 2011) Legislative: Population-Based Health Dataseis - Part I: An Overview Advocating Evidence-Based Health Policy OJIN: The Online Journal of Issues in Nursing Vol. 16 No. 3. DOI: 10.3912/OJIN.Voll6No03LegCol01 Health agencies within the United States (U.S.) federal government have a strong history of gathering and organizing a wealth of data on a variety of health indicators. The data, collected mainly through survey methods and medical-record reviews, are complied into various dataseis and are usually available free of charge for analysis. These dataseis, commonly referred to as health databases/ have been used to conduct original research studies within various fields, such as epidemiology, health services research, nursing, sociology, and demography. Research studies conducted with these databases have documented health disparities (Braveman. Cubbin. Egerter. Williams. & Pamuk. 2010: Centers for Disease Control and Prevention. 2005: Powe. Tarver-Carr. Eberhardt. & Brancati. 2003: Scharoun-Lee. Adair. Kaufman. & Gordon-Larsen. 2009) monitored the progress of various health indicators (Bernert et al.. 2010: Dietz. Callaghan. Morrow. & Cogswell. 2006: Jones et al.. 2009); and provided recommendations for health policy IHonberg. McPherson. Strickland. Gage. & Newacheck. 2005: Kogan et a!.. 2010: McPherson et al.. 2004: Ormand. Spillman. Waidmann. Caswell. & Tereschenko. 2011: Parish. Shattuck. & Rose. 2009). Population-based health databases are beneficial not only to nurse researchers, but also to nurses within practice and educational settings who can use health indicators for developing evidence-based interventions and health policy. The purpose of this Legislative Column (Part 1) is to increase understanding of the benefits and limitations of population-based health databases as a possible reference source for developing interventions and health policy. The next Legislative Column. Part 2 will provide an example of how one database, the National Survey of Children's Health, was used to determine prevalence rates of children with a medical home and explore associations between race/ethnicity and medical homes. In this present column I will discuss the benefits and limitations of population-based health databases, describe available resources and considerations in using these resources to answer health-related questions, and present an original research study using the National Survey of Children's Health Database. Benefits and Limitations Two major benefits of using population-based health databases include the ability to generalize findings and the cost effectiveness of using these databases. The term population-based' usually implies the data were collected through rigorous, probability-sampling methods. Results from probability sampling can be generalized to an entire population. Samples in some databases, such as the National Survey for Children's Health, can be generalized to the population of an individual state. However, the majority of population-based health databases represent a national sample and cannot be generalized to people residing in a state or a smaller area. The major advantage of probability sampling is that this method surpasses a convenience sample or a sample limited to a distinct subset of participants because one can generalize the findings of studies using probability sampling. The second benefit to using databases is related to cost-effectiveness. It would be quite expensive and somewhat prohibitive for a researcher, practitioner, or policy analyst to collect all the data compiled within a health database (Moriartv et al.. 1999I. The collection and organization of data through stringent data collection protocols have already been done by federal government researchers, or their contractors (McArt & McDougal. 2005: Moldanado. . A majority of these released databases are available for anyone to download from government websites and are either free or available for a small fee. …