Measles Vaccines and Misinformation in the Courts: A Snapshot From the KFF Health Misinformation Tracking Poll

This KFF Health Misinformation Tracking Poll was designed and analyzed by public opinion researchers at KFF. The survey was conducted February 20-28,2024, online and by telephone among a nationally representative sample of 1,316 U.S. adults in English (1,226) and in Spanish (90). The sample includes 1,036 adults (n=51 in Spanish) reached through the SSRS Opinion Panel either online (n=1,011) or over the phone (n=25). The SSRS Opinion Panel is a nationally representative probability-based panel where panel members are recruited randomly in one of two ways: (a) Through invitations mailed to respondents randomly sampled from an Address-Based Sample (ABS) provided by Marketing Systems Groups (MSG) through the U.S. Postal Service’s Computerized Delivery Sequence (CDS); (b) from a dual-frame random digit dial (RDD) sample provided by MSG. For the online panel component, invitations were sent to panel members by email followed by up to three reminder emails.

Another 280 (n=39 in Spanish) interviews were conducted from a random digit dial telephone sample of prepaid cell phone numbers obtained through MSG. Phone numbers used for the prepaid cell phone component were randomly generated from a cell phone sampling frame with disproportionate stratification aimed at reaching Hispanic and non-Hispanic Black respondents. Stratification was based on incidence of the race/ethnicity groups within each frame.

Respondents in the phone samples received a $15 incentive via a check received by mail, and web respondents received a $5 electronic gift card incentive (some harder-to-reach groups received a $10 electronic gift card). In order to ensure data quality, cases were removed if they failed two or more quality checks: (1) attention check questions in the online version of the questionnaire, (2) had over 30% item non-response, or (3) had a length less than one quarter of the mean length by mode. Based on this criterion, no cases were removed.

The combined cell phone and panel samples were weighted to match the sample’s demographics to the national U.S. adult population using data from the Census Bureau’s 2023 Current Population Survey (CPS), September 2021 Volunteering and Civic Life Supplement data from the CPS, and the 2023 KFF Benchmarking survey with ABS and prepaid cell phone samples. The demographic variables included in weighting for the general population sample are sex, age, education, race/ethnicity, region, civic engagement, frequency of internet use, political party identification by race/ethnicity, and education. The sample of registered voters was weighted separately to match the U.S. registered voter population using parameters above plus recalled vote in the 2020 presidential election by county quintiles grouped by Trump vote share. Both weights account for differences in the probability of selection for each sample type (prepaid cell phone and panel). This includes adjustment for the sample design and geographic stratification of the cell phone sample, within household probability of selection, and the design of the panel-recruitment procedure.

In addition, the sample of parents (n=283) includes adults from the SSRS opinion panel who say that they are a parent or guardian of a child 18 years or younger living in their home was weighted separately to the Census Bureau’s 2023 Current Population Survey (CPS) and the 2023 KFF Benchmarking survey. The demographic variables included in weighting for the parent sample are sex, age, education, race/ethnicity, and political party.

The margin of sampling error including the design effect for the full sample is plus or minus 3 percentage points and for registered voters is plus or minus 4 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. Sampling error is only one of many potential sources of error and there may be other unmeasured error in this or any other public opinion poll. KFF public opinion and survey research is a charter member of the Transparency Initiative of the American Association for Public Opinion Research.

Group N (unweighted) M.O.S.E.
Total 1,316 ± 3 percentage points
Total parents 283 ± 7 percentage points
Party ID
Democrats 398 ± 6 percentage points
Independents 338 ± 7 percentage points
Republicans 407 ± 6 percentage points




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