New YouGov/CBS News polls survey caucus goers and primary voters in Iowa, New Hampshire and South Carolina
The YouGov/CBS News 2016 Battleground Tracker is based on surveys of registered voters who had previously voted in primaries in Iowa, New Hampshire and South Carolina. The poll was conducted online but included registered voters who were contacted by phone. The sample includes 459 likely Democratic primary voters in New Hampshire, 380 in South Carolina, and 602 likely caucus voters in Iowa. On the GOP side, the sample includes 519 likely Republican primary voters in New Hampshire, 852 in South Carolina, and 534 likely caucus voters in Iowa. The majority of respondents are recontacts, meaning most also participated in the November wave of the poll. See a more detailed description of the methodology used here.