YouGov conducted a survey of 1252 Iowa registered voters between Dec 14 and Dec 17, 2015. Respondents were contacted by either Telephone, Internet or Opt-In and the interaction was automated. The results of this poll were released on Dec 20, 2015.
The poll was sponsored by CBS News.
Results were provided for the only publicly acknowledged question.
Question 3 | PreferenceView Matchup
Which candidate are you most likely to vote for in the Iowa Democratic Presidential caucus in 2016?
This question was presented to 459 likely voters from Iowa who were contacted in some undisclosed fashion. The margin of sampling error is ± 8.6%.
The question wording was provided by YouGov and CBS News.