1. Can Survey Design Reduce the Undercount of Public Health Insurance Coverage?
By: Brian Robertson, PhD; Mark Noyes, MPH
Problem Statement
Undercounts of Medicaid populations are well known and persistent when measuring health insurance.
Many surveys rely on the traditional design to obtain information about insurance coverage. Surveys that use such a design include ACS, BRFSS, NHIS, and SIPP.
Factors in Identifying Medicaid Coverage that Survey Design Needs to Consider
This modified traditional design identified
76% to 95% of Medicaid Enrollees.
 Fac
State Specific Factors
Topic
Potential problem
Oregon
Rhode Island
South Dakota
Vermont
Program Name
Identify coverage as the program name
Oregon Health Plan
RIte Care
Medicaid
Green Mountain Care
Plan Name
Identify with a specific plan name
Healthy Kids (Medicaid program for children)
Rhody Health Partners, Connect Care Choice 
Dr. Dynasaur (Medicaid program for children)
MCO or CCO
Identify with the care organization through which they receive care
Numerous
PC Plus
Medicaid Program Administration
Identify coverage as the insurance carrier, confusing with private coverage
State
Private insurance carriers
Enrollment method
Identify insurance as the Exchange or Obamacare confusing with private coverage
State portal or the Federal Exchange
State Exchange: HealthSource RI
State Exchange: Vermont Health Connect
Type of Government Insurance
Identify insurance with where it was obtained or applied for
"Government" insurance, through the government, through SSI, welfare, disability
Similarity in names can lead to confusion
Confusing Medicaid with Medicare
Other Factors
Identify by other program names
Medicaid often combined with Indian Health Services
Original Medicaid expansion program prior to ACA was phased out but was still identified as a type of coverage
Identify the coverage as employer sponsored private insurance
Premium assistance programs using Medicaid funds to purchase employer sponsored insurance
An Example: American Community Survey
Is this person CURRENTLY covered by any of the following types of health insurance or health coverage plans? Mark "Yes" or "No" for EACH type of coverage  
Insurance through a current or former employer or union (of this person or another family member)
Insurance purchased directly from an insurance company (by this person or another family member)
Medicare, for people 65 and older, or people with certain disabilities
Medicaid, Medical Assistance, or any kind of government-assistance plan for those with low incomes or a disability
TRICARE or other military health care
VA (including those who have ever used or enrolled for VA health care)
Indian Health Service
Any other type of health insurance or health coverage plan – Specify
Hypothesis
The majority of the Medicaid undercount in surveys arises from limitations of the traditional design of health care coverage plan questions.
Modifying the traditional design will more accurately capture Medicaid enrollment.
Our research is based on health insurance surveys conducted in four states from 2014 – 2017 among 20,500 households. Each survey was conducted by telephone.
We have used this methodology since 2001, conducting more than 113,000 surveys in 7 states, gathering data on 284,000 individuals.
Those in green can be addressed by modifying the traditional design
Those is red require follow-ups to verify the type of coverage
But even our modified traditional design missed
5% to 24% of those with Medicaid.
Identifying these enrollees required follow-ups beyond the traditional design.
Approach
Modify the traditional design while adding follow-ups in cases where there may be confusion.
Expand the traditional design answer categories to include:
The state specific name(s) of Medicaid (typically done but not always),
The name of the Medicaid program administrator [Unread],
The name of the Medicaid managed care organization [Unread],
A category for the state specific Exchange, “The Exchange,” “Obamacare” [Unread], and
A category for “through the government,” “government insurance,” “Disability,” “SSI” [Unread].
Add follow-ups where there may be confusion to determine the type of coverage.
Exchange coverage, government insurance, Medicare vs. Medicaid
Even if insurance is identified as private, determine if it is Medicaid by checking:
The insurance provider or carrier in states where Medicaid is administered by private carriers (follow-up to determine if the insurance is provided through Medicaid),
The source of insurance (identified as through the government, by the Medicaid plan name or plan administrator), and
If ESI is provided through premium assistance program (in states offering these programs).
For all follow-ups: Provide clarifying information to assist respondent in identifying the type of coverage.
Conclusions
Survey design is an important method of reducing Medicaid undercounts. The use of the traditional design will miss a significant percentage of Medicaid enrollees.
Even a modified traditional design will miss a sizeable percentage of Medicaid enrollees.
Surveys must be tailored to individual states based on program names, enrollment structure, Medicaid administration, and other factors.
However, survey design cannot completely eliminate the Medicaid undercount, factors like social desirability remain in play.
We would like to thank the following organizations for their use of data:
HealthSource RI & Freedman Healthcare; South Dakota Department of Social Services; Oregon Health Authority; The Vermont Department of Health & Vermont Department of Financial Regulation Insurance Division