This section provides an overview of data issues that users of Healthy People 2020 data should be aware of.
Each measurable objective contains a data source and a national baseline value. The baselines use valid and reliable data derived from currently established, and where possible, nationally representative data systems. Baseline data provide the point from which a 2020 target is set.
For each measurable objective, an Operational Definition describes the methodology for assessing progress. The Operational Definition defines the measure and includes information about the data source, baseline details (numerator, denominator, and questions used to collect the data), target, target-setting method, and other relevant items. If, over time, the changes are made to the data or any of the components related to assessing progress, the data and/or operational definition will be updated to reflect the revisions.
Data used to track the Healthy People 2020 objectives are based on events occurring in the 50 States and the District of Columbia, where available. Unless specifically noted, all objectives exclude data for U.S. territories. The data used to track most population-based Healthy People 2020 objectives are derived from either a national census of events (for example, the National Vital Statistics System) or from nationally representative sample surveys (for example, the National Health Interview Survey).
For some objectives, however, complete national data are not available and data for selected States and/or areas are used to monitor the objectives. In these cases, the coverage area is described within the data table for the objective and in the operational definitions. Examples of these sub-national data systems include the Health Care Cost and Utilization Project and the Toxic Exposure Surveillance System. Data for these objectives may not be representative of the United States as a whole. If during the decade national data become available, they will be used to track the objectives.
For some national data systems that cover the entire United States, such as the Behavioral Risk Factor Surveillance System, data are not available for some variables for all States. This is either because data for a specific variable are not collected by some States or because the quality of data for some States is not sufficient to produce reliable estimates for some variables. The number of reporting States can vary from year to year. This information is also shown in the operational definitions for selected objectives.