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.
Introductory
Articles
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…
The purpose of this knowledge base article is to 1) present an overview of International Classification of Disease (ICD) codes and versions available, 2) describe where researchers can find these codes in the Medicare claims, and 3) understand how ICD codes appear in the data.
CMS began offering quarterly claims and enrollment data with Quarter 3, 2015. This article describes the quarterly data file creation, availability, and pricing.
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.
Researchers may now request Research Identifiable File (RIF) Medicare data on a quarterly basis, in addition to the annual files.Data available on a quarterly basis includes 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.
Under changes to the Part 2 regulations on January 17, 2017, CMS is now permitted to include substance use disorder claims data in the Research Identifiable Files (RIFs).  Research Identifiable Files shipped or extracted in the VRDC after 05/22/2017 are no longer subject to the redaction.
To provide estimated file sizes for recent, commonly requested 5% and 100% Research Identifiable Files.
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. 
Medicare-paid observation stays may be found in the Medicare Outpatient, Inpatient, or MedPAR files. This article describes how to identify observation stays that appear in each as defined by CMS billing guidance.
This article describes the difference between two similiar variables in the carrier file -the Line NCH Payment Amount and Line Provider Payment Amount.
This article explains possible discrepancies when using the outpatient file to calculate payment amounts at the claim level and revenue center level.
This article provides instructions on how to open the Medicare Physician/Supplier Procedure Summary Master (PSPS) file in Microsoft Access or SAS.
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 requesting and using the data.