Knowledgebase

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.
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Introductory
Articles
Differences between RIF, LDS, and PUF Data Files
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,…
Federal Regulations Governing the Release of CMS Data
This article describes the Federal Regulations that govern the release of CMS data for research.
Strengths and Limitations of CMS Administrative Data in 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…
Popular
Articles
How to Identify Hospital Claims for Emergency Room Visits in the Medicare Claims Data
This article provides guidance on how to identify hospital emergency room claims from the Medicare files.
Diagnosis and Procedure Coding Resources
Providers that bill Medicare use codes for patient diagnoses and codes for care, equipment, and medications provided. This articles provides resources to identify the codes…
CMS Cell Size Suppression Policy
To describe the CMS cell size suppression policy and provide examples of common scenarios and possible options.

Featured Article

Provider Variables in Medicare Fee-for-Service and Encounter Data
There are many different provider variables in the Medicare Fee-for-Service (FFS) Claims and Encounter data. Researchers are often interested in the performing NPI and/or the facility CCN or organizational NPI, but other variables are sometimes…
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RIF Medicare Quarterly Data
Researchers may request Research Identifiable File (RIF) Medicare data on a quarterly basis, in addition to the annual files. Data available on a quarterly basis includes Medicare Research Identifiable FFS claims (Inpatient, Outpatient, Home Health Agency, Hospice, Skilled Nursing Facility, Carrier, and Durable Medical Equipment) and the Master Beneficiary Summary File: Base A/B segment.
Medicare Limited Data Set (LDS) Quarterly Claims and Enrollment Data
CMS began offering quarterly claims and enrollment data with Quarter 3, 2015. This article describes the quarterly data file creation, availability, and pricing.
Differences between MCBS PUF and LDS Data Files
This article is designed to provide a brief overview of the differences between the Medicare Current Beneficiary Survey (MCBS) Public Use File (PUF) and MCBS Limited Data Set (LDS) files so researchers can decide which file is appropriate for their study needs.
Differences between RIF, LDS, and PUF Data Files
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, and research identifiable files.
Differences between the Inpatient and MedPAR Files
Researchers who are interested in studying inpatient utilization (e.g. hospital stays) have two options: the Inpatient claims file or the Medicare Provider Analysis and Review (MedPAR) file. It is important to note that the differences between the two files will vary depending on whether a researcher is interested in the Research Identifiable File (RIF) or Limited Data Set (LDS) versions of the two files.
Medicare Inpatient File, LDS or RIF: Counting Distinct Hospitalizations
Hospitals may submit multiple claims for some hospitalizations. This article provides guidance for counting distinct inpatient hospitalizations and for sequencing claims for each distinct hospitalization found in the Inpatient Research Identifiable File (RIF) and Limited Data Set (LDS) files. This guidance is not applicable to the MedPAR because each record in that file is already a distinct hospitalization.
How to Identify Hospital Claims for Emergency Room Visits in the Medicare Claims Data
This article provides guidance on how to identify hospital emergency room claims from the Medicare files.
BSA Prescription Drug Event (PDE) PUF - Linking the Drug Name variable to RxNorm
Provide the steps to identify the drug name from the RxNorm database for the NDCs in the BSA PDE PUF. 
Inclusion of Hospital and Skilled Nursing Stays in the RIF Annual MedPAR and Claims Data
Researchers working with the Research Identifiable (RIF) MedPAR or Inpatient and Skilled Nursing Facility (SNF) claims may find records that do not appear to correspond to the year of the file. This article explains these instances. 
Difference Between Line Payment Amounts in Carrier File
This article describes the difference between two similiar variables in the carrier file -the Line NCH Payment Amount and Line Provider Payment Amount.
Discrepancy in the Outpatient Claim Payment Amount and Sum of the Revenue Center Payment Amounts
This article explains possible discrepancies when using the outpatient file to calculate payment amounts at the claim level and revenue center level.