KFF COVID-19 Vaccine Monitor: January 2023

This KFF Health Tracking Poll/COVID-19 Vaccine Monitor Poll was designed and analyzed by public opinion researchers at the Kaiser Family Foundation (KFF). The survey was conducted January 17 – January 24, 2023, online and by telephone among a nationally representative sample of 1,234 U.S. adults in English (1,180) and in Spanish (54). The sample includes 1,005 adults reached through the SSRS Opinion Panel either online or over the phone (n=25 in Spanish). 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. 980 panel members completed the survey online and panel members who do not use the internet were reached by phone (25).

Another 229 (n=29 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).

The online questionnaire included two questions designed to establish that respondents were paying attention. Cases that failed both attention check questions, those with over 30% item non-response, and cases with a length less than one quarter of the mean length by mode were flagged and reviewed. Cases were removed from the data if they failed two or more of these quality checks. 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 2021 Current Population Survey (CPS). Weighting parameters included sex, age, education, race/ethnicity, region, and education. The sample was weighted to match patterns of civic engagement from the September 2017 Volunteering and Civic Life Supplement data from the CPS and to match frequency of internet use from the National Public Opinion Reference Survey (NPORS) for Pew Research Center.  Finally, the sample was weighted to match patterns of political party identification based on a parameter derived from recent ABS polls conducted by SSRS polls. The weights take into account 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.

The margin of sampling error including the design effect for the full sample 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. Kaiser Family Foundation public opinion and survey research is a charter member of the Transparency Initiative of the American Association for Public Opinion Research.