METHODOLOGY:
HOW THE POLL WAS CONDUCTED AND THE MARGIN OF ERROR CALCULATED
The CBS News 2016 Battleground Tracker is a panel study based on interviews conducted on the internet of registered voters in Arizona, Colorado, Florida, Georgia, Iowa, Michigan, North Carolina, New Hampshire,Nevada, Ohio, Pennsylvania, Virginia, Wisconsin, California, Illinois, Indiana, New Jersey, New York, South Carolina, and Texas.
The poll was conducted by YouGov, an online polling organization.The most recent wave interviewed registered voters on August 30-September 2, 2016 in thirteen bat-tleground states (Arizona, Colorado, Florida, Georgia, Iowa, Michigan, North Carolina, New Hampshire,Nevada, Ohio, Pennsylvania, Virginia, and Wisconsin) and combined single state polls in North Carolina and Pennsylvania.The first wave was fielded between September 3-10, 2015, with 4860 respondents, and the second wavefieldwork was completed between October 15-22, 2015, with 3952 respondents and the third wave between November 15-19, 2015. The fourth wave was fielded between December 13-17, 2015.
The majority of the2nd-4th wave respondents are recontacted panelists. The first 4 waves consist of interviews in Iowa, New Hampshire, and South Carolina only. The fifth wave added new interviews in Florida, Georgia, and Texas,and was completed between January 17-21, 2016. The sixth wave was fielded only in South Carolina, with interviews completed February 10-12, 2016. The seventh wave was fielded also in February, among panelists in Georgia, Texas, and Virginia.
The eighth wave fielded February 22-26, 2016, and recontacted panelists from the January wave in Georgia and Texas. Virginia respondents were all new to the panel. The ninth wave was fielded to new respondents in Michigan from March 2-4, 2016, and in addition, respondents in Florida, Illinois, and Ohio were contacted March 9-11, 2016. Respondents in New York, Pennsylvania, and Wisconsin were contacted March 29-April 1, 2016 for the tenth wave. In the eleventh wave of our primary surveys, respondents in California, New York, and Pennsylvania were contacted April 13-15, 2016. The twelveth was conducted April 20-22, 2016 and interviewed panelists in Indiana and Pennsylvania.
The thirteenth wave was the first general election poll, and was conducted of registered voters in Florida and Ohio May 16-19, 2016. The fourteenth wave was fielded May 31-June 3, 2016, and consists of registered voters in California and New Jersey, interviewing both those likely to vote in the November general election and the upcoming Democratic primary election.
The fifteenth wave of the Battleground Tracker interviewed registered voters in Colorado, Florida, North Carolina, and Wisconsin from June 21-24, 2016.The July waves were conducted before and after the conventions. These waves interviewed registered voters on July 13-15, 2016 in eleven battleground states (Colorado, Florida, Iowa, Michigan, North Carolina,New Hampshire, Nevada, Ohio, Pennsylvania, Virginia, and Wisconsin) and combined single state polls in Iowa, Michigan, and Ohio.
All YouGov respondents were recontacted July 15-16, 2016 for a follow-up survey on the Trump Vice Presidential announcement, were recontacted again July 22-23, 2016 for a follow-up survey at the conclusion of the Republican National Convention, and finally recontacted July 29-30, 2016for a follow-up survey at the conclusion of the Democratic National Convention.The seventeenth wave interviewed registered voters in Arizona, Nevada, and Virginia on August 2-5,2016. The eighteen wave interviewed registered voters in Florida, Georgia, and New Hampshire on August10-12, 2016. The eighteenth interviewed registered voters in Iowa and Ohio on August 17-19, 2016.Respondents were selected from YouGovs and two other online panels. These are “opt-in” panels which are open for anyone to join. However, YouGov also randomly selected persons from voter registration lists who had previously voted in primary elections and contacted them by phone. A total of 24017 registered voters were contacted by phone and the YouGov sample includes 1821 phone recruits.Recontact rates ranged from 34% to 75% for each state for the reinterview waves. In addition, new respondents were selected from the YouGov panel each wave.For the October, November, and December waves, all respondents from previous waves were contacted to participate. In the January wave, all respondents from previous waves in Iowa, New Hampshire, and South Carolina were contacted to participate. Florida, Georgia, and Texas are completely new interviews. In the February wave, all respondents from previous South Carolina waves were contacted to participate. In the March wave, all respondents from the previous Florida wave were invited to participate. All respondents from the New York survey in late March were invited to participate in the April wave. In the June 21-24