Margaret "Maggie" Colby

Maggie Colby

Associate Director
Areas of Expertise
  • Medicaid data sources
  • Program and policy evaluation
  • Technical assistance
  • Measurement for program monitoring
  • Learning collaboratives
  • Medicaid and CHIP
  • Care Delivery Systems
  • State Health Policy
About Maggie

Margaret (Maggie) Colby focuses on Medicaid, state, and local health policy and is an expert in the policy intersections between Medicaid and the new health insurance marketplaces. Colby has led major technical assistance projects as well as several multimethod evaluations that combine rigorous quantitative analyses with case studies, examining changes in enrollment, retention, access, and service utilization caused by changes in provider or beneficiary incentives.

Colby currently leads an evaluation of states that pursued alternative Medicaid expansion strategies via 1115 waivers and advises the Centers for Medicare & Medicaid Services on evaluation and monitoring plans for these states. She is also evaluating an intervention that delivers scheduled and urgent house calls on a 24/7 basis to Medicaid beneficiaries with complex chronic conditions, using an integrated care team that includes medical, behavioral, and social service providers. 

Colby previously directed the Medicaid and CHIP Learning Collaboratives, which bring together state and federal officials to support the development of integrated and high-performing Medicaid and state marketplace systems that fulfill the requirements of the Affordable Care Act. She also supported California in developing public reports that present application, eligibility, and enrollment data for both Medi-Cal and Covered California. She has served as a task leader and researcher on evaluation studies for the Assistant Secretary for Planning and Evaluation, the California Health Care Foundation, and state and local governments, including evaluations of Express Lane Eligibility, the Healthy Indiana Plan, California’s Health-e-App Public Access System, Healthy San Francisco, and the alignment of Medicaid and Medicare enrollment for dual eligible beneficiaries in Arizona. 

Colby, who joined Mathematica in 2007, has published work in Health Services Research, the Maternal and Child Health Journal, Medical Care Research and Review, and the American Journal of Pharmacy Benefits. She holds an M.P.P. from Georgetown University.

Key Projects
  • Evaluating Express Lane Eligibility

    Express Lane Eligibility allows a state’s Medicaid and/or CHIP program to rely on another public agency’s eligibility findings to qualify children for public health insurance coverage. Mathematica evaluated ELE in the Medicaid and CHIP programs.