Medicare And Medicaid At 50

The Medicare and Medicaid at 50 survey was designed and analyzed by researchers at the Kaiser Family Foundation (KFF). The survey was conducted by telephone from April 23 through May 31, 2015 among a nationally representative random digit dial sample of 1,849 adults ages 18 or older living in the U.S., including Alaska and Hawaii (note: persons without a telephone could not be included in the random selection process). Computer-assisted telephone interviews conducted by landline (748) and cell phone (1101, including 646 who had no landline telephone) were carried out in English and Spanish by SSRS. SSRS collaborated with KFF researchers on sample design, weighting, pretesting, and supervised the fieldwork. KFF paid for all costs associated with the survey.

To capture the views and experiences of those most impacted by Medicare and Medicaid, the survey included oversamples of people ages 65 and older, people between the ages of 55 and 64, and those who are either personally covered by Medicaid or whose children are covered by Medicaid. To oversample these populations, the sample plan consisted of three elements: (1) general population respondents reached by RDD landline (n=617) or cell phone (n=989); (2) respondents reached by RDD landline, but interviewed only if they were 65 or older (n=27); (3) respondents reached by calling back phone numbers where respondents previously interviewed indicated that they or their child were covered by Medicaid (n=216).  Both the random digit dial landline and cell phone samples were provided by Marketing Systems Group (MSG).

A multi-stage weighting process was applied to ensure an accurate representation of the national adult population. The first stage of weighting involved corrections for sample design, including accounting for the likelihood of non-resonse for the re-contact sample, number of eligible household numbers for those reached via landline, and a correction to account for the fact that respondents with both a landline and cell phone have a higher probability of selection. In the second weighting stage, the sample was weighted to match estimates for the national population using data from the Census Bureau’s 2014 March supplement of the Current Population Survey (CPS), and the distribution of phone use was estimated based on the CDC’s National Health Interview Survey (NHIS). The weighting parameters used were age and gender, race/ethnicity, education, marital status, census region, population density of the respondent’s county, and telephone use. Through the weighting process, each oversample is adjusted so that the group is represented in proportion to their actual share of the population.

The margin of sampling error including the design effect for the full sample is plus or minus 3 percentage points. Numbers of respondents and margins 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. Kaiser Family Foundation public opinion and survey research is a charter member of the Transparency Initiative of the American Association for Public Opinion Research.