This repository is an effort to save hourly electoral prediction data from the information markets at PredictIt.org.

We can quantify odds over time by scraping the market's API every day and creating a database of hourly prices.

2022

During 2022, the 24-hour price history of various markets was saved each day after 11:00 PM ET.

The JSON file returned for each request was saved to a separate file.

2020

During 2020, the 24-hour price history of various markets was saved each day after 11:00 PM ET.

As of July 4th 2020, there were 89 individual race markets being tracked.

Each day's prices were appended to a comma-separated text file, with 1 row per contract per hour. The markets tracked were from three categories:

Presidential

1. Which party will win the U.S. presidential election? (2721)
2. What will be the Electoral College margin? (6653)
3. What will be the popular vote margin? (6663)
4. Individual markets for every state (e.g, Florida) (5544)

Senate

1. Which party will control the Senate after the election? (4366)
2. What will be the net change in seats, by party? (6670)
3. Which race will be won by the smallest margin? (6737)
4. Individual markets for most races (e.g., Maine class II) (5811)

House

1. Which party will control the House after 2020 election? (4365)
2. How many seats will Democrats win? (6669)
3. Individual markets for some races (e.g., South Carolina 1st) (6753)

2018

Historical daily price data for the 2018 midterm elections was provided by PredictIt as part of an academic research agreement. A list of 120 congressional election markets was submitted on November 4, 2018 and data was returned on December 17, 2018.

Each of the markets in 2018 focused on a single House or Senate election:

1. Will Elizabeth Warren be re-elected? (2918)
2. Will Pelosi be re-elected? (3450)

2016

Historical data for elections in 2016 were similarly provided. A list of 34 markets was submitted on October 17, 2018 and data was returned on November 3, 2018.

Markets in 2016 focused on either party control or a single election:

1. Will the GOP control both Congress and the White House after 2016? (1250)
2. Individual markets for some races (e.g., Louisiana senate race) (2157)

Supplementary 90-day price history for Presidential markets was save in 2022.