ResDAC has developed over 100 articles that cover topics ranging from the CMS data request process through using the data for a study. CMS has developed additional resources, including TAF data quality briefs and TAF data quality state snapshots, examining the quality of the Medicaid data.
CMS offers files from aggregate data to individual person level data. This article describes the differences between the aggregate, public use files, the limited data sets,…
This article describes the Federal Regulations that govern the release of CMS data for research.
The purpose of this article is to identify 1) common strengths of Medicare and Medicaid administrative data and 2)  broad limitations for researchers to consider when…
Beginning in 2008, some hospital provider numbers appearing in the claims contain a “V” in the fifth position of the six-digit Medicare Provider Number. Usually, the fifth position is a number, not a character. These hospital provider numbers appear in the MedPAR, Inpatient and Outpatient files for both RIF and LDS versions.  ResDAC recommends that researchers remove these claims.
This article provides resources for obtaining statistics and reports related to the Medicare and Medicaid programs and their beneficiaries. The following Medicare/Medicaid statistical and summary data resources address some of the most common requests for this type of information. These are by no means exhaustive.
The beneficiary eligibility and enrollment files have changed in content and name over the years. It is important to understand the timing of these changes and the unique features of each file if you are using older files or see them referenced in articles.
CMS offers several claim-level files that contain outpatient claims; that is, facility claims submitted for care covered under Part B. Three versions of the LDS files are described:Outpatient file,Outpatient Prospective Payment System (OPPS) file, and OPPS Partial Hospitalization file.
The Internet Archive is a useful resource for finding historical copies of the Centers for Medicare and Medicaid Services (CMS) websites, reports or statistics that are no longer available.
The purpose of this article is to provide CMS’s definition of uncompensated care, the years collected, and location in the Medicare hospital cost report forms.
The Medicare cost report files are created by Fiscal Year. The definition used to create the fiscal year files vary depending on the provider type.
This article provides a brief overview of the SEER-Medicare linked database.
Researchers who are interested in requesting the Health and Retirement Study (HRS) data linked to Medicare data will need to go through both a HRS and CMS review of their request. This document provides a brief overview of that process.
Detailed information about Medicare Part D drug plan formularies is available in two CMS data files. Important differences in the files are outlined below, including whether or not the files can be linked to other data sources.
The CMS National Plan and Provider Enumeration System (NPPES) provides basic information about all organization and individual providers with a National Provider Identifier (NPI).  This article provides a brief overview of how to access the NPPES and the information that it contains.
The purpose of this article is to define a Long-Term Care Hospital (LTCH) and to identify the files that contain claims submitted by a LTCH.