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README.md

FiveThirtyEight's Pollster Ratings

This directory contains the data behind FiveThirtyEight's pollster ratings.

See also:

Past data:

pollster-stats-full.xlsx contains a spreadsheet with all of the summary data and calculations involved in determining the pollster ratings as well as descriptions for each column.

pollster-ratings.csv has ratings and calculations for each pollster. A copy of this data and descriptions for each column can also be found in pollster-stats-full.xlsx.

raw-polls.csv contains all of the polls analyzed to give each pollster a grade. Descriptions for each column are in the table below.

Header Definition
pollno FiveThirtyEight poll ID number
race Election polled
year Year of election (not year of poll)
location Location (state or Congressional district, or "US" for national polls)
type_simple Type of election (5 categories)
type_detail Detailed type of election (this distinguishes between Republican and Democratic primaries, for example, whereas type_simple does not)
pollster Pollster name
partisan Flag for internal/partisan poll. "D" indicates Democratic poll, "R" indicates Republican poll, "I" indicates poll put out by independent candidate's campaign. Note that different sources define these categories differently and our categorization will often reflect the original source's definition. In other words, these definitions may be inconsistent and should be used carefully.
polldate Median field date of the poll
samplesize Sample size of the poll. Where missing, this is estimated from the poll's margin of error, or similar polls conducted by the same polling firm. A sample size of 600 is used if no better estimate is available.
cand1_name Name of Candidate #1. Candidates #1 and #2 are defined as the top two finishers in the election (regardless of whether or not they were the top two candidates in the poll). In races where a Democrat and a Republican were the top two finishers, Candidate #1 is the Democrat and simply listed as "Democrat".
cand1_pct Candidate #1's share of the vote in the poll.
cand2_name Name of Candidate #2. Candidates #1 and #2 are defined as the top two finishers in the election (regardless of whether or not they were the top two candidates in the poll). In races where a Democrat and a Republican were the top two finishers, Candidate #2 is the Republican and simply listed as "Republican"
cand2_pct Candidate #2's share of the vote in the poll.
cand3_pct Share of the vote for the top candidate listed in the poll, other than Candidate #1 and Candidate #2.
margin_poll Projected margin of victory (defeat) for Candidate #1. This is calculated as cand1_pct - cand2_pct. In races between a Democrat and a Republican, positive values indicate a Democratic lead; negative values a Repubican lead.
electiondate Date of election
cand1_actual Actual share of vote for Candidate #1
cand2_actual Actual share of vote for Candidate #2
margin_actual Actual margin in the election. This is calculated as cand1_actual - cand2_actual. In races between a Democrat and a Republican, positive values indicate a Democratic win; negative values a Republican win.
error Absolute value of the difference between the actual and polled result. This is calculated as abs(margin_poll - margin_actual)
bias Statistical bias of the poll. This is calculated only for races in which the top two finishers were a Democrat and a Republican. It is calculated as margin_poll - margin_actual. Positive values indicate a Democratic bias (the Democrat did better in the poll than the election). Negative values indicate a Republican bias.
rightcall Flag to indicate whether the pollster called the outcome correctly, i.e. whether the candidate they had listed in 1st place won the election. A 1 indicates a correct call and a 0 an incorrect call; 0.5 indicates that the pollster had two or more candidates tied for the lead and one of the tied candidates won.
comment Additional information, such as alternate names for the poll.