What is 538

All scientifically-conducted polls are included provided that they meet our reporting requirements and the internal poll rule see below. What are the reporting requirements for a poll? At a minimum, the poll must list 1 the percentage of the vote for each major candidate — not simply the margin; 2 the sample size; and 3 the dates that the poll was in the field. Do you list internal polls that are leaked by the campaigns?

This site has a ban on listing internal polls. The logic behind this is that when an interested party conducts a poll, it is only liable to leak its results to the public only if it contains good news for their candidate, thereby encouraging donors, press persons, etc. But it does mean that there may be a bias in which information becomes part of the public record: we learn about a poll that has a candidate ahead by 10 points in a state, but not one where he is down by 2.

For this reason, such polls are excluded. More specifically, a poll is excluded if it was conducted by any current candidate for office, a registered campaign committee, a Political Action Committee, or a group, unless i the poll has a bipartisan partner partisan polling groups will sometimes pair with one another to reduce the perception of bias , or ii the organization has a long and demonstrable track record of releasing all its data to the public.

Polls are not excluded simply because the pollster has conducted work on behalf of Republican or Democratic candidates, provided that the particular poll in question was intended for public consumption. It will indicate the median date of interviewing for that poll — not when that poll was reported or posted to the site. For example, a poll which conducted interviews on July 1, July 2 and July 3, and was reported to the media on July 5, would be listed with a date of July 2.

What if a pollster provides multiple versions of their poll — e. When these situations arise:. After that, I will use the likely voter version;. What is the purpose of the trendline adjustment? Polling data comes out in different increments in different states. Some states are polled frequently, while others are only polled only occasionally.

The trendline adjustment is an effort to correct for this problem by using polling movement in states that have been polled recently to adjust the data in states that have not been. If a particular state is polled in the midst of a bounced cause by something like the conventions, such pollig may reflect only a temporary, near-term fluctuation rather than the longer-term demographic reality.

To take a more concrete example, suppose that Virginia was last polled in the weekend prior to the Democratic convention, and that poll showed John McCain ahead by 2 points. Suppose also that North Carolina was last polled in the weekend following the Democratic convention, and that poll showed Barack Obama ahead by 4 points. Looking at these two polls might give the impression that North Carolina is a better state for Barack Obama than Virginia.

The trendline adjustment attempts to correct for this. How does the trendline adjustment work? In plain English, we look at movement in the polling in recently-polled states and in national polls to predict movement in other states. For the original methodology behind the trendline adjustment, please see here. For subsequent refinements to the methodology, please see here , here , here and here. Does the trendline adjustment assume that polling movement is uniform between different states? No, it does not.

The adjustment attempts to account for which particular demographic groups are responsible for the polling movement, and those groups may produce differing results in different states. See here and here for discussion.

Does the trendline adjustment account for the convention bounce? We will have a special set of procedures in place on and around the time of the conventions to account for the convention bounce, but they have not yet been fully developed.

Are the polls weighted for purposes of calculating the trendline adjustment? More reliable polls have more influence in the computation of the trendline. Step 3. The Regression Estimate.

What is the regression estimate? Put differently, it is a way not to be held hostage by the results of individual polls that might defy common sense, particularly where polling data in a state is sparse. Polls are an imperfect measure of voter sentiment, subject to the vagaries of small sample size, poor methodology, and transient blips and trends in the numbers. Since North Dakota and South Dakota are very similar, it is unlikely that there is a true eight-point differential in the polling in these states.

The regression estimate is able to sniff out such discrepancies. For general background on the process of regression analysis, see here. What is the dependent variable in the regression analysis? Technically speaking, there are two regressions that are computed in each state. The second is a regression on the total committed vote held by either of the major-party candidates. What independent variables are included in the regression estimate? The regression models evaluate a total of 16 candidate variables.

The 16 variables presently considered by the model are as follows: Political. Fundraising Share. The total share of funds raised in that state by each candidate expressed specifically as the percentage of all funds raised that were raised by the Democratic candidate. An adjustment is made to caucus states to account for their higher proclivity to vote for Barack Obama.

In Michigan, the variable is based on the results of exit polling, which indicated who voters would have selected if all candidates were on the ballot. Liberal-Conservative Likert Score.

The most liberal state, Massachusetts, has a Likert score of 5. The most conservative, Utah, has a score of 3. Religious Identity 5. The proportion of white evangelical protestants in each state. The proportion of Catholics in each state.

The proportion of LDS voters in each state. Ethnic and Racial Identity 8. The proportion of African-Americans in each state. The number of Latino voters in each state as a proportion of overall voter turnout in , as estimated by the Census Bureau.

The reason I use data based on turnout rather than data based on the underlying population of Latinos is because Latino registration and turnout varies significantly from state to state. It is much higher in New Mexico, for instance, which has many Hispanics who have been in the country for generations, than it is in Nevada, where many Hispanics are new migrants and are not yet registered. See discussion here. Economic Per capita income in each state.

The proportion of jobs in each state that are in the manufacturing sector. Demographic The proportion of the white population aged 65 or older in each state.

Because life expectancy varies significantly among different ethnic groups, this version has more explanatory significance than when looking at the entire white and non-white population. The proportion of residents aged in each state, as a fraction of the overall adult population.. Average number of years of schooling completed for adults aged 25 and older in each state. The proportion of voters in each state that live in suburban environments, per exit polls.

How often is the regression updated? The regression updates automatically based on the latest polling data. Periodically, I will also test out new variables for potential inclusion in the model. What is the snapshot? It is i the combination of the trend-adjusted polling average Step 2 with our regression estimate Step 3. This represents our best estimate of what would happen if the election were held today.

How much weight is given to the regression estimate? Therefore, the regression estimate will have comparatively substantial weight in states with little polling data, but very little weight in states with robust polling data. What is the projection? It is our best estimate of what will happen when the election is actually held in November. How does the projection differ from the snapshot? It differs in two important ways. Firstly, current polling leads are mean-reverted.

Secondly, undecided voters are allocated to the two major-party candidates. How does the mean-reversion adjustment work? There has been an extremely robust tendency in Presidential elections for national polling numbers to revert to the mean as the election approaches — that is, for the trailing candidate to gain ground.

The further we are out from the election, the more tightening in the polls we can expect. For example, a point national lead held days before the election projects, on average, to only about an 8-pont victory on Election Day, whereas a 5-point lead held 60 days before the election projects to about a 4-point victory.

This adjustment is described in much more detail here. Is the mean-reversion adjustment applied uniformly across all states?

The mean-reversion adjustment is based on the notion that national polling data will tighten as the election nears. This does not necessarily imply that polling in any particular state will tighten.

Instead, we first calculate the overall degree of mean-reversion expected in the national popular vote, and then imprint it on individual states through the process described here. States that have been more sensitive to movement in the national numbers will receive a larger degree of mean-reversion. How are undecided voters allocated? This process may seem to work slightly backward.

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If this is incorrect, please email us to let us know. If you agree, please consider funding our work. We believe political bias should be transparent. Presidential candidates on the Michigan ballot submit a list of 16 qualified electors to the Secretary of State's Office. The 16 electors whose candidate wins Michigan's popular vote will participate in the Electoral College at the State Capitol in December. Electors pledge to support the candidate they represent and may not vote otherwise.

Michigan voters can be assured that all 16 Michigan electoral votes automatically go to the presidential candidate winning the popular vote. Most states distribute their Electoral College votes in the same "winner takes all" fashion as Michigan. However two states, Maine and Nebraska, apportion their electoral votes by congressional district. To be elected president, a candidate must receive at least of the electoral votes cast nationwide.

If no candidate receives votes, the final decision is made by the U. House of Representatives. Only two American presidents have been chosen by the U.

House of Representatives because they lacked enough Electoral College votes.