For more than 20 years, the Dartmouth Atlas Project has documented
glaring variations in how medical resources are distributed and used in
the United States. The project uses Medicare data to provide
comprehensive information and analysis about national, regional, and
local markets, as well as individual hospitals and their affiliated
These reports and the research upon which they are based have helped
policymakers, the media, health care analysts and others improve their
understanding of the efficiency and effectiveness of our health care
system. This valuable data forms the foundation for many of the ongoing
efforts to improve health and health systems across America.
This web site provides access to all Atlas reports and publications,
as well as interactive tools to allow visitors to view specific regions
and perform their own comparisons and analyses. These tools have helped
other groups create reports like those listed on our Case Studies page.
Further studies and data created with the support of the National
Institute on Aging can be found here.
The goal of one study was to develop an instrument and conduct a survey
of Medicare beneficiaries, and to better understand the causes and
consequences of geographic variation in per capita expenditures for
During each annual CMS data file update, trend files of the year-to-year counts of the diagnosis and procedure codes used in the MedPAR, Part B, and Outpatient claims files are generated. Each of the codes includes both the short and long name. These coding trends are useful for researchers to determine if there was a change (increase/decrease) over time that may indicate that a code is obsolete or a different code is being used to capture a particular diagnosis or procedure. The Coding Trends files can be found on our Downloads page.