Health Insurance Marketplace: December Enrollment Report. Appendix B. Methodology and Technical Notes


The data that are reported in this issue brief have been generated by the information systems of the Centers for Medicare & Medicaid Services, based on information reported to CMS by SBMs, and information collected by the FFM for states with HHS- supported or fully run Marketplaces (including those run in partnership with states).

Unless otherwise noted, the data in this issue brief represent cumulative Marketplace enrollment-related activity for the 10-1-13 to 11-30-13 reporting period, with information available as of 12-10-13.

We believe that the information contained in this issue brief provides the most systematic “snapshot” of enrollment-related activity in the Marketplaces to date because the data for the various metrics are counted using comparable definitions for data elements across states, and between the SBMs and FFM (see table below). It is important to note that the SBM enrollment-related data that are reported in this issue brief represent state data that have been reported to CMS, and may differ from comparable data that have previously been publicly reported on SBM websites or in media reports because that data may be based on different time periods or metric definitions from those used in this report.

While this issue brief includes some data for all states, data for certain metrics are not available for some states due to information system issues. For example, CMS did not receive data on some metrics for certain states, as noted in Appendix A.

The following section provides highlights of major methodological changes since the November Marketplace Enrollment Report. For additional technical information about the metrics that are included in this report, please refer to the November Marketplace Report.7

7 U.S. Department of Health and Human Services Office of the Assistant Secretary for Planning and Evaluation (ASPE), “Health Insurance Marketplace: November Enrollment Report, November 13, 2013,” ASPE Issue Brief, which can be accessed at

View full report


"ib_2013dec_enrollment.pdf" (pdf, 217.64Kb)

Note: Documents in PDF format require the Adobe Acrobat Reader®. If you experience problems with PDF documents, please download the latest version of the Reader®