California's Uninsured on the Eve of ACA Open Enrollment
This report is based on findings from the first of what is expected to be a four-wave panel survey by the Kaiser Family Foundation (KFF). KFF plans to conduct the subsequent waves in early 2014, late 2014, and early 2015, with those surveys focusing on the coverage choices people make; experiences with enrollment and access to care; as well as tracking any changes in knowledge, attitudes, health expenses, and sense of financial security. All surveys will be conducted with the original random probability sample panel of respondents, whether they obtain coverage or remain uninsured.
The current survey was designed and analyzed by public opinion researchers at KFF, led by Mollyann Brodie, Ph.D., including Claudia Deane, Liz Hamel, and Sarah Cho, with input from Larry Levitt, Gary Claxton, and Rachel Garfield. Social Science Research Solutions (SSRS) collaborated with KFF researchers on sample design and weighting, and supervised the fieldwork.
The survey was conducted by telephone from July 11 through August 29, 2013, among a representative random sample of 2,001 adults ages 19-64 living in California, who reported having been without health insurance coverage for at least two months at the time of interview1 (note: persons without a telephone could not be included in the random selection process). Computer-assisted telephone interviews conducted by landline (990) and cell phone (1,011, including 660 who had no landline telephone) were carried out in English and Spanish2 by SSRS. Both the random digit dial landline and cell phone samples were generated through Marketing Systems Group’s GENESYS sampling system.
Because the study targeted a low-incidence population, the sample was designed to increase efficiency in reaching this group. To do so, both the landline and cell phone sampling frames oversampled areas with a lower-income population (since being uninsured is negatively correlated with income). The landline sample frame also oversampled households whose phone numbers were matched with directory listings indicating the presence of at least one person age 19-64 and a household income of less than $25,000. Additionally, 230 interviews (130 landline, 100 cell phone) were conducted with respondents who previously completed recent national SSRS omnibus surveys of the general public and indicated they were ages 19-64 and uninsured. These previous surveys were conducted with nationally representative, random-digit-dial landline and cell phone samples.
Screening for the survey involved verifying that the respondent (or another member of the household for the landline sample) met the criteria of: 1) residing in California; 2) being 19-64 years old; and 3) being currently uninsured. For the landline sample, if two or more household members met the criteria, a respondent was randomly selected by asking for the qualified person who had the most recent birthday. Selected respondents were further screened to confirm that they had been uninsured for at least two months.
A multi-stage weighting design was applied to ensure an accurate representation of the California uninsured population ages 19-64. The weighting process involved corrections for sample design, as well as sample weighting to match known demographics of the target population. The base weight accounted for the oversamples used in the sample design, as well as the likelihood of non-response for the re-contact sample, number of eligible household members for the landline sample, and a correction to account for the fact that respondents with both a landline and cell phone have a higher probability of selection. Demographic weighting parameters were based on the 19-64 year old uninsured California population using the Census Bureau’s 2011 American Community Survey (ACS) for age, education, race/ethnicity, nativity (for Hispanics only), Hispanics by gender, presence of own child in the household, marital status, California region, and poverty level.3 The sample was also weighted to match current patterns of telephone use among the uninsured in California using an estimate based on data from the July-December 2012 National Health Interview Survey combined with the weighted distribution of phone status among 996 uninsured California residents who completed interviews on SSRS omnibus surveys over the past year. All statistical tests of significance account for the effect of weighting.
The margin of sampling error including the design effect for the sample of eligible uninsured, on which most findings in the report are based, is plus or minus 4 percentage points. Numbers of respondents and margin of sampling error for key subgroups are shown in the table below.
|Total CA uninsured
|+ 3 percentage points
|Eligible uninsured (citizens/permanent residents)4
|+ 4 percentage points
|Eligible uninsured by income group5
|Eligible uninsured, < 138% FPL (Medi-Cal target group)
|+ 5 percentage points
|Eligible uninsured, >138%-400% FPL (exchange subsidy target group)
|+ 6 percentage points
|Eligible uninsured, >400% FPL
|+ 13 percentage points
|+ 7 percentage points
For results based on other subgroups, the margin of sampling error may be higher. Sample sizes and margin of sampling errors 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.