The Burden of Medical Debt: Results from the Kaiser Family Foundation/New York Times Medical Bills Survey

Appendix 2: Survey Methodology

The Kaiser Family Foundation/New York Times Medical Bills Survey is based on interviews with a probability-based sample of 2,575 respondents between the ages of 18 and 64 conducted August 28 through September 28, 2015. Interviews were administered online and by telephone in English and Spanish, including a longer interview with 1,204 adults who reported problems paying household medical bills in the past 12 months and a shorter comparison survey with 1,371 who did not report such problems. Teams from the Foundation and The Times worked together to develop the questionnaire and analyze the data, and both organizations contributed financing for the survey. Each organization is solely responsible for its content.

NORC at the University of Chicago conducted sampling, interviewing, and tabulation for the survey using the AmeriSpeak Panel, a representative panel of adults age 18 and over living in the United States. AmeriSpeak Panel members are recruited through probability sampling methods using the NORC National Sample Frame, an address-based sampling frame. Panel members who do not have internet access complete surveys via telephone, and internet users complete surveys via the web (for the current survey, 619 respondents completed via phone and 1,956 via web).

The combined results have been weighted to adjust for the fact that not all survey respondents were selected with the same probability, to address the implications of sample design, and to account for systematic nonresponse along known population parameters. The first weighting stage addressed differences in probability of selection for the AmeriSpeak Panel and to account for differential nonresponse to the AmeriSpeak screening interview. At this stage, an adjustment was also made to account for the undersampling of panelists who did not report problems paying household medical bills and to account for differential nonresponse to the survey screening interview.

In the second weighting stage, the sample was adjusted to match known demographic distributions of the U.S. population ages 18-64 by age, gender, education, race/ethnicity, Census region, and household income. Demographic weighting parameters were based on the U.S. Census Bureau’s 2015 March Supplement to the Current Population Survey.

The margin of sampling error including the design effect for the full sample is plus or minus 3 percentage points.  All statistical tests of significance account for the effect of weighting. Numbers of respondents and margin of sampling error for key subgroups are shown in the table below. For results based on other subgroups, the margin of sampling error may be higher. Sample sizes and margins of sampling error for other subgroups are available by request. Note that sampling error is only one of many potential sources of error in this or any other public opinion poll.

Group	N (unweighted)	M.O.S.E.
Total adults ages 18-64	2,575	±3 percentage points
Problems paying household medical bills past 12 months	1,204	±4 percentage points
No problems paying household medical bills past 12 months	1,371	±4 percentage points
Insured with problems paying household medical bills past 12 months	802	±5 percentage points
Uninsured with problems paying household medical bills past 12 months	369	±8 percentage points

Kaiser Family Foundation public opinion and survey research and NORC at the University of Chicago are both charter members of the Transparency Initiative of the American Association for Public Opinion Research.