class: center, middle, inverse, title-slide # Questions about the Statistics + U.S. Elections ### Prof. Maria Tackett --- class: middle ### What are the different ways that pollsters determine likely voters vs. registered voters? Have those methods changed at all since 2016? ### What does that mean for a race where a lot of energy on both sides is going in to turning out the vote rather than just persuading "moderates." (I'll leave this to the campaign strategists 🙃) --- ## Adults vs. registered vs. likely voters .vocab[Adults:] People in the U.S. ages 18 and older .vocab[Registered voters:] People registered to vote. - Usually determined by a straightforward survey question about whether respondent is registered to vote in their election distribution .vocab[Likely voters:] More representative of the likely voter electorate --- - Ask a series of questions about interest in upcoming election, past election participation, and intention to vote in upcoming election. - Some adjustments made, e.g. adjustments made for young people ineligible to vote in previous elections - Use models to predict the likelihood a respondent will vote - Some pollsters now asking if respondents have already voted **More info:** - [Marist Poll General Informaiton](http://maristpoll.marist.edu/methods/#sthash.5MX15H28.dpbs) - See [likely voter survey questions](https://scri.siena.edu/about-us/likely-voter-methodology/) from Sienna College Research Institute --- class: middle ### It has been said that the so-called "hidden votes" gave president Trump an edge in the last election, contradicting the polls. How has that been addressed after four years, if at all possible? --- - There is little evidence of the "shy" Trump voter - Study by the [American Association for Public Opinion Research](https://www.aapor.org/Education-Resources/Reports/An-Evaluation-of-2016-Election-Polls-in-the-U-S.aspx) found that "interviewer administered polls did not under-estimate Trump’s support more than self-administered IVR (interactive voice response) and online surveys". -- - In 2016, many state-level polls underestimated the number of white voters without a four-year college degree. - Most polls have started weighting by education to reduce over-weighting of people with a college degree in the sample -- - In general, some groups of people are hard to reach, so pollsters have to apply statistical methods to re-weight their sample, i.e. make it more representative of the actual electorate (not just representative of who responds to a poll) --- ### Read more about sampling weights - [An Evaluation of 2016 Election Polls in the US](https://www.aapor.org/Education-Resources/Reports/An-Evaluation-of-2016-Election-Polls-in-the-U-S.aspx) by the American Association for Public Opinion Research - [Trump Supporters Aren’t ‘Shy,’ But Polls Could Still Be Missing Some Of Them](https://fivethirtyeight.com/features/trump-supporters-arent-shy-but-polls-could-still-be-missing-some-of-them/) by FiveThirtyEight - [A Resource for State Preelection Polling](https://www.pewresearch.org/methods/2020/08/18/a-resource-for-state-preelection-polling/) by Pew Research --- class: middle ### Same as the candidates' campaigns, are election statistical analyses also focused mainly on "swing" states? --- Though the discussion may focus primarily on swing states, statisticians are interested in all of the states! There is useful information to be learned about variability and error in predictions even from states where the outcome is unsurprising. -- .pull-left[ ### Scenario 1 | | Predicted | Actual | Error | |-------------|-----------|---------|-------| | Candidate A | **51%** | 49.5% | -1.5% | | **Candidate B** | 49% | **50.5%** | +1.5% | **General consensus**: 😕 **Statistician**: 😄 ] -- .pull-right[ ### Scenario 2 | | Predicted | Actual | Error | |-------------|-----------|---------|-------| | **Candidate A** | **65%** | **55%** | -10% | | Candidate B | 35% | 45% | +10% | **General consensus**: 🙂 **Statistician**: 😱 ] --- ### How long does it take for statistical models to be affected by current events,like a scandal? Statistical models are primarily rely on polling data, so they take current events into account only as quickly as the polls do. --- class: middle ### Also how accurate are models really, when Hillary was favored by a decent margin four years ago and still lost? ### What are some types of prediction model used, and what is more efficient? For example in the last election, there are many newspapers (if not say a lot) would predict Hillary to win, and some were against the odds to predict Trump win (and he actually did). --- ## Are models accurate? Models produce probabilities, not final answers! (Think about your logistic regression models.) - In 2016: FiveThirtyEight gave Trump a 30% chance to win the day before the election; the Upshot forecast gave him an 15% chance. - Rare events do happen! **March Madness** 🏀 - Is 15% or 30% really that rare? --- ## Are models accurate? But, the models weren't perfect... -- - In 2016, state polling errors were largely in the same direction - Clinton over-performed in a lot of blue states and under-performed in key Midwest states (**that's a problem! errors should be random**) -- - Issues with polling get baked into the model (bad data in, bad data out). -- - Some models didn't accurately account for correlation between states, especially in the Midwest. -- - Uncertainty was not effectively communicated to the general public --- ## Read more reflections on 2016 models - [An Evaluation of 2016 Election Polls in the US](https://www.aapor.org/Education-Resources/Reports/An-Evaluation-of-2016-Election-Polls-in-the-U-S.aspx) by the American Association for Public Opinion Research - [The Real Story of 2016](https://fivethirtyeight.com/features/the-real-story-of-2016/) by FiveThirtyEight - [Presidental Forecast Post- Mortem](https://www.nytimes.com/2016/11/16/upshot/presidential-forecast-postmortem.html#commentsContainer) by the Upshot --- ## Final thoughts - Focus on state polls, not national polls! -- - Don't read too much into early results - Can be potentially misleading based on who is expected to vote early, use mail-in voting, or vote on election day -- - There is a lot of uncertainty this year! -- - Don't let predictions affect your behavior! **VOTE!** --- ## FiveThirtyEight election forecasts <img src="img/fivethirtyeight.png" width="55%" style="display: block; margin: auto;" /> .midi[Screenshot on Nov 2 of [FiveThirtyEight election forecasts](https://projects.fivethirtyeight.com/2020-election-forecast/?cid=rrpromo)].