Oregon Health Insurance Experiment, 2007-2010 (ICPSR 34314)

Version Date: May 2, 2014 View help for published

Principal Investigator(s): View help for Principal Investigator(s)
Amy Finkelstein, Massachusetts Institute of Technology and National Bureau of Economic Research; Katherine Baicker, Harvard University and National Bureau of Economic Research


Version V3

Oregon Health Study

In 2008, a group of uninsured low-income adults in Oregon was selected by lottery to be given the chance to apply for Medicaid. This lottery provides an opportunity to gauge the effects of expanding access to public health insurance on the health care use, financial strain, and health of low-income adults using a randomized controlled design. The Oregon Health Insurance Experiment follows and compares those selected in the lottery (treatment group) with those not selected (control group). The data collected and provided here include data from in-person interviews, three mail surveys, emergency department records, and administrative records on Medicaid enrollment, the initial lottery sign-up list, welfare benefits, and mortality.

This data collection has seven data files:

Dataset 1 contains administrative data on the lottery from the state of Oregon. These data include demographic characteristics that were recorded when individuals signed up for the lottery, date of lottery draw, and information on who was selected for the lottery, applied for the lotteried Medicaid plan if selected, and whose application for the lotteried plan was approved. Also included are Oregon mortality data for 2008 and 2009.

Dataset 2 contains information from the state of Oregon on the individuals' participation in Medicaid, Supplemental Nutrition Assistance Program (SNAP), and Temporary Assistance to Needy Families (TANF).

Datasets 3-5 contain the data from the initial, six month, and 12 month mail surveys, respectively. Topics covered by the surveys include demographic characteristics; health insurance, access to health care and health care utilization; health care needs, experiences, and costs; overall health status and changes in health; and depression and medical conditions and use of medications to treat them.

Dataset 6 contains an analysis subset of the variables from the in-person interviews. Topics covered by the survey questionnaire include overall health, health insurance coverage, health care access, health care utilization, conditions and treatments, health behaviors, medical and dental costs, and demographic characteristics. The interviewers also obtained blood pressure and anthropometric measurements and collected dried blood spots to measure levels of cholesterol, glycated hemoglobin and C-reactive protein.

Dataset 7 contains an analysis subset of the variables the study obtained for all emergency department (ED) visits to twelve hospitals in the Portland area during 2007-2009. These variables capture total hospital costs, ED costs, and the number of ED visits categorized by time of the visit (daytime weekday or nighttime and weekends), necessity of the visit (emergent, ED care needed, non-preventable; emergent, ED care needed, preventable; emergent, primary care treatable), ambulatory case sensitive status, whether or not the patient was hospitalized, and the reason for the visit (e.g., injury, abdominal pain, chest pain, headache, and mental disorders).

The collection also includes a ZIP archive (Dataset 8) with Stata programs that replicate analyses reported in three articles by the principal investigators and others:

Finkelstein, Amy et al "The Oregon Health Insurance Experiment: Evidence from the First Year". The Quarterly Journal of Economics. August 2012. Vol 127(3).

Baicker, Katherine et al "The Oregon Experiment - Effects of Medicaid on Clinical Outcomes". New England Journal of Medicine. 2 May 2013. Vol 368(18).

Taubman, Sarah et al "Medicaid Increases Emergency Department Use: Evidence from Oregon's Health Insurance Experiment". Science. 2 Jan 2014.

Finkelstein, Amy, and Baicker, Katherine. Oregon Health Insurance Experiment, 2007-2010. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2014-05-02. https://doi.org/10.3886/ICPSR34314.v3

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Robert Wood Johnson Foundation (64301), United States Department of Health and Human Services. National Institutes of Health. National Institute on Aging (P30AG012810, RC2AG036631 and R01AG0345151), Smith Richardson Foundation (2008-775), Alfred P. Sloan Foundation (6-26-2008), United States Department of Health and Human Services. Office of the Assistant Secretary for Planning and Evaluation (3P30-AG012810-15S1), California HealthCare Foundation (08-1433), John D. and Catherine T. MacArthur Foundation (09-93341-000-HCD), United States Social Security Administration (5 RRC 08098400-03-00), United States Department of Health and Human Services. Centers for Medicare and Medicaid Services

As explained in the ICPSR Processing Notes in the codebook, Dataset 7 and many variables in Datasets 1-6 are restricted from general dissemination for reasons of confidentiality. Users interested in obtaining the restricted variables must complete an Agreement for the Use of Confidential Data, specify the reasons for the request, and obtain IRB approval or notice of exemption for their research. Apply for access to the restricted data through the ICPSR restricted data contract portal.

Inter-university Consortium for Political and Social Research
2007 -- 2010
2007 -- 2010

Additional information about this study is available on www.nber.org/oregon.

The Oregon Health Insurance Experiment collected hospital discharge and credit report data which were not provided to ICPSR.

Dataset 6 contains only the variables required to replicate the analysis in the article by Baicker et al (2013). The principal investigators did not provide any other data collected during fielding of the in-person survey.

Dataset 7 contains only the variables required to replicate the analysis in Taubman et al (2014). The principal investigators did not provide any other data collected from the emergency department visits in the Portland area.

The original lottery list provided by the state contained 100,600 records of persons who signed up for the lottery. The study group pared down this list to 74,922 individuals by removing duplicate and deactivated records; individuals who were not eligible for the lotteried program because they were too old, too young, or gave an address outside of Oregon; individuals who lived at institutional addresses or who were signed up by an unrelated third party; individuals with multiple active records on the lottery list; and those who died prior to the lottery notification date. The data files in this collection only cover these 74,922 individuals, of which 29,834 were selected by the lottery.

Both the initial and 12 month mail surveys were administered to the same 29,589 treatment and 28,816 control cases. The six month survey was limited to a subsample of these cases: 5,312 treatment and 7,712 control cases. The initial survey respondents could respond my mail and phone, the six month respondents by mail only, and the 12 month respondents by mail, phone, and Web. The initial mail survey was fielded during June 2008-November 2008, the six month survey during January 2009-May 2009, and the twelve month survey during July 2009-March 2010.

The in-person survey was conducted from August 2009 until October 2010. For logistical reasons, the study sample was limited to the Portland area and included 10,405 individuals select in the lottery and 10,340 control cases.


The individuals registered for Oregon's 2008 Medicaid lottery constitute the study universe. The lotteried health insurance plan, Oregon Health Plan Standard (OHP Standard), is a Medicaid expansion program that covers low-income adults who are not categorically eligible for Medicaid. Specifically, it covers adults ages 19-64 not otherwise eligible for public insurance who are Oregon residents, are United States citizens or legal immigrants, have been without health insurance for six months, have income below the federal poverty level, and have assets below $2,000. From January 28 to February 28, 2008 anyone could be added to the lottery list by telephone, by fax, in person sign-up, by mail, or online. Individuals could register themselves and other adults 19 or older in their household.

administrative records data, experimental data, medical records, survey data

For the mail surveys, the response rates were 45 percent for the initial survey, 49 percent for the six month survey, and 41 percent for the 12 month survey. For the in-person survey the response rate was 59 percent.

Patient Health Questionnaire-9 (PHQ-9) Total Severity Score

SF-8 Health Survey Physical Component Score

SF-8 Health Survey Mental Component Score

Framingham Risk Score


2018-02-15 The citation of this study may have changed due to the new version control system that has been implemented. The previous citation was:
  • Finkelstein, Amy, and Katherine Baicker. Oregon Health Insurance Experiment, 2007-2010. ICPSR34314-v3. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2014-05-02. http://doi.org/10.3886/ICPSR34314.v3

2014-05-02 The principal investigators deleted the variable dt_death (label = Date of Death: Oregon Vital Statistics Data). This variable was in Dataset 1 (Descriptive Variables).

2014-04-10 The second note of the ICPSR Processing Notes in the codebook was corrected.

2014-04-10 Dataset 6 (In-person Survey), Dataset 7 (Emergency Department Data), and Stata replication code for the analyses in Baicker et al (2013) and Taubman et al (2014) were added to the collection. The study title and codebook were revised accordingly. The replication code is now available as Dataset 8.

2014-04-10 A typo in the codebook cover was corrected.

2013-12-05 ICPSR added a list of the Oregon Health Insurance Experiment grants to the codebook.

2013-12-02 ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:

  • Checked for undocumented or out-of-range codes.


  • The public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.

  • One or more files in this data collection have special restrictions. Restricted data files are not available for direct download from the website; click on the Restricted Data button to learn more.

  • The citation of this study may have changed due to the new version control system that has been implemented. Please see version history for more details.
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This study is maintained and distributed by the Health and Medical Care Archive (HMCA). HMCA is the official data archive of the Robert Wood Johnson Foundation.