National Sample Election Forecast

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2016

Survey Methods

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Election Forecast The 2020 USC Dornsife Presidential Election Poll is tracking changes in Americans' opinions throughout a campaign for the White House. Around 6000 respondents in our representative panel are asked questions every other week on what they care about most in the election, and on their attitudes toward their preferred candidates. The "Daybreak poll" is updated just after midnight every day of the week. Each day’s data point represents the estimate among voters over the previous fourteen days, representing the poll;s full sample. We also offer a 7-day graph which shows more variation due to it relying on a half sample. For more information about the poll and its available data and information, visit the survey methods tab. Why we have changed to show a 14-day average graphic on our front page: (You may need to hold the shift key and then refresh the page to see it)

To have a demographically balanced sample across the observation period for every 14-day tracking poll wave, each participant in our survey panel has the option to respond to questions during a specific range of days, twice a month. Our original 7-day graphic represented opinions from half our respondents, recorded each day and including responses from the previous 7 days. Since respondents are invited to respond every 14 days, the 7-day graphic was subject to a certain level of periodicity, since the sample on which the graph was based essentially repeats every other week. Our goal for this graphic was to have it more nimbly reflect reactions to news events than it could if the full 14 day wave was included in each data point. The 7-day graphic is now available under the "all graphs" tab. Our original 7-day graphic represented opinions from half our respondents, recorded each day and including responses from the previous 7 days. Since respondents are invited to respond every 14 days, the 7-day graphic was subject to a certain level of periodicity, since the sample on which the graph was based essentially repeats every other week. Our goal for this graphic was to have it more nimbly reflect reactions to news events than it could if the full 14 day wave was included in each data point. The 7-day graphic is now available under the "all graphs" tab.



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2016 The 2016 USC Dornsife / LA Times Presidential Election Poll followed the pioneering approach we first adopted in the RAND Continuous 2012 Presidential election poll, by tracking changes in Americans' opinions throughout the 2016 campaign for the White House. More than 4500 respondents who are members of our representative online panel were asked questions on their voting intentions, what they cared about most in the election, and on their attitudes toward their preferred candidates. The "2016 Daybreak poll" was updated just after midnight every day of the week.



Our final poll measured Donald Trump with a three point lead. This was widely misunderstood to mean that we were one of the few polls to predict Donald Trump’s win in the electoral college. In fact, Hillary Clinton was the winner of the national popular vote, by 2 percentage points.



As we had always intended, we revisited our experimental poll to consider what had worked well and what could be improved. Our examination of sampling and weighting methods revealed that we had an overrepresentation of rural voters in our sample, a possibility that we simply overlooked at the time, as rurality is not a typical weighting variable.



When we adjusted our poll according to census benchmarks for rural/urban population, our final estimate had Hillary Clinton over Donald Trump by a one point margin. We of course would have preferred to have that outcome on November 4, 2016, but we were pleased to find where our error lay and to be able to correct it. More information in our Q&A about this poll.



The poll was part of the ongoing Understanding America Study: (UAS) at the University of Southern California’s (USC) Dornsife Center for Economic and Social Research, It was conducted in partnership with the then Jesse M. Unruh Institute of Politics (now Center for the Political Future) and the Los Angeles Times.



Every day, we invited one-seventh of the members of the UAS election panel to answer three predictive questions: What is the percent chance that… (1) you will vote in the presidential election? (2) you will vote for Clinton, Trump, or someone else? and (3) Clinton, Trump or someone else will win? As their answers come in, we update the charts daily (just after midnight) with an average of all of the prior week’s responses. To find out more about what lies behind the vote, each week we also ask respondents one or two extra questions about their preferences and values. The team responsible for the USC Dornsife/LA Times Presidential Election Poll four years ago developed the successful RAND Continuous Presidential Election Poll, which was based on the same methodology. For more information, documents and data, please visit the Understanding America Study’s elections page.

Survey Methods Tracking Poll Design



On August 11, 2020, USC’s Center for Economic and Social Research (CESR) invited 8,355 eligible voters who are active members of CESR’s Understanding America Study (UAS) probability-based internet panel to participate in an ongoing election tracking survey. The baseline data and consent information was collected in UAS survey 306.



Each study member who agreed to participate was randomized to respond on a pre-assigned day of the week, distributed so that our full sample participates over a 14-day period. Respondents have until their next assigned wave day (or 14 days after their assigned date) to complete the survey. Data for the full sample is nearly complete after the first 14 days, but not final until the end of the full 28-day wave.



We provide four models of the presidential vote: probability-based personal voting, estimates based on expectations of how others in the respondent’s state are voting, expectations about how respondents’ social circle is voting, and a categorical vote estimation among a group of likely voters who are asked who they would vote for it the election were held today. The categorical vote question explicitly asks about the Democratic, Republican, Green and Libertarian candidates by name and party. All others ask about the two main candidates and "someone else". For information specific to this tracking poll including question text, survey design, weighting, and contact information, please consult our tracking poll methodology document.



Tracking Graphs



The daily updated data points in the graphs on this site represent estimates of the national vote for Donald Trump (red line) and Joe Biden (blue line), using the four models. These are calculated based on the previous fourteen-day or seven-day cumulative responses to the tracking poll. The gray bars represent the margin of error for each estimate. Differences between the estimated vote for the two main candidates is not statistically significant if the lines are in the gray area.



Information and Documentation



Survey questionnaires, toplines, press releases, and graphics will be made available from our 2020 Election Data page, along with details about how we sample and weight the tracking poll. Check out our Q&A for information about this poll, and similarities and differences in methodology between 2016 and 2020. For detailed information about the Understanding America Study online panel design, including sampling, recruitment, weighting, and attrition, please visit the methodology section of our UAS data pages.



Public Use Data files



Microdata files are available to registered UAS data users for download from our 2020 Election Data site. To register, visit our registration page.