California Simulation of Insurance Markets (CalSIM)


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CalSIM: Modeling the future of health care


As California implements the Affordable Care Act (ACA) its leaders require a good understanding of what the likely impacts of the law will be on its residents – and the state’s budget. To help them, the UCLA Center for Health Policy Research and the UC Berkeley Center for Labor Research and Education created the California Simulation of Insurance Markets (CalSIM), a micro-simulation model that can be used to estimate the impact of various elements of the ACA. CalSIM uses a wide range of official data sources, including the California Health Interview Survey.  
To date, CalSIM has helped California’s state and local health officials, medical providers, community representatives, insurance companies and others to understand the likely enrollment of Californians in an expanded Medi-Cal as well as in the state’s new health insurance exchange, Covered California. It has helped project how the “individual mandate” might impact coverage as well as who will be left out of new health care reform efforts.
The California Endowment, The California Health Benefit Exchange (Covered California), the Blue Shield of California Foundation, and the California Pan-Ethnic Health Network provided funding for the development of CalSIM and analyses.
    CalSIM was developed in the Center’s Health Economics and Evaluation Research (HEER) Program​. For more information about CalSIM, please contact:


    Gerald Kominski, PhD
    Director, UCLA Center for Health Policy Research
    Principal Investigator, CalSIM
    Phone: 310-794-2681
    Publications using CalSIM include: 
    Policy Briefs, Notes and Reports:
    Webinars and Presentations:
    Predicting Response to the Affordable Care Act: Will Californians Take Advantage of New Options ​(Oct. 2012):         
    Health Care Coverage in California under the Affordable Care Act (presentation to the California Health Benefit Exchange Board, March 2012) 
    The Potential Impact of the Affordable Care Act in California ​(presentation to California Health Benefit Exchange Board, May 2011):