Frequently Asked Questions About the Data Collections in HMCA

What are the components of a data collection in HMCA?

A data collection comprises one or more data files, plus technical documentation that describes the data. SAS, SPSS, and/or Stata setups are included with many collections.

Data files are often provided in multiple data formats. Every data file is supplied as an ASCII text file and, for many collections, in at least one other format as well, such as Stata files, SPSS portable files, and SAS transport files generated by the SAS XPORT engine or SAS CPORT procedure. SPSS portable and SAS transport files are the most common data formats besides ASCII.

Technical documentation typically includes the following:

  • study description that summarizes the collection
  • file manifest
  • bibliography of related literature
  • description of the study's methodology
  • data collection instrument(s)
  • data map/record layout of the ASCII data file(s)
  • variable descriptions
  • univariate frequencies (for most collections)

Study descriptions, file manifests, and bibliographies of related literature are presented as separate files. Other components of the documentation may be bundled in a single file or distributed among multiple files. Documentation files are provided in Portable Document Format (PDF) and/or as ASCII text files.

The setups, which usually contain complete variable and value labels and often include missing value declarations or recodes, can be used to create software-specific system files (e.g., SAS datasets) from the ASCII data files.

How are the holdings of HMCA organized?

The data collections in HMCA are organized according to their main subject matter, using a five-category classification scheme:

  1. Health Care Providers
  2. Cost/Access to Health Care
  3. Substance Abuse & Health
  4. Chronic Health Conditions
  5. Other

How can I obtain a HMCA data collection?

All HMCA data, setup, and documentation files are freely available to the general public. Anyone can download all of the public-use files in any HMCA collection from our Web site.

How can I obtain restricted HMCA Data?

Every data collection is examined by HMCA staff for confidentiality issues. Variables that pose a disclosure risk are restricted from general dissemination. Restricted variables are removed from the public-use datasets available on our Web site or are modified in a way that limits disclosure. For example, a variable that gives respondents' ages in single years may be recoded to five-year age groups and topcoded at 75 so that age 16 becomes age 15-19 and age 92 becomes 75+.

To obtain restricted variables in their original form, analysts must agree to the terms and conditions of a restricted data use agreement. These legally binding agreements place strict controls on who may access restricted data and how the data are used, stored, and conveyed.

If a data collection has any restricted data, that will be noted under "Access Notes" on its home page (e.g., To apply for the restricted data follow the link under "Access Notes."

How do I deposit a data collection with HMCA?

We recommend that you use ICPSR's Web-based, electronic Data Deposit Form to securely upload data collected under grants from the Robert Wood Johnson Foundation.

The electronic form enables the depositor to describe the data collection being deposited and to designate others to access and add information to the form if desired. It does not need to be completed in one session. If you encounter any technical issues with the form or have questions, please contact

Alternatively, if you cannot or prefer not to use the electronic procedure, please complete the ICPSR Data Deposit Form (PDF 61K - Word 47K) and mail it, together with the data and technical documentation, to one of the addresses shown below. Submit your data files and any electronic documentation on removable media such as CD-ROMs. Do not send your collection in an e-mail attachment or by FTP.

Address for shipment via U.S. Postal Service:

University of Michigan
P.O. Box 1248
Ann Arbor, MI 48106-1248

Address for shipment by carriers that require a street address, e.g., UPS:

University of Michigan
330 Packard Street
Ann Arbor, MI 48104

For information on preparing your data collection in a manner that is optimally useful for secondary analysis, see the ICPSR Guide to Social Science Data Preparation and Archiving, 5th Edition.