The RAND Continuous 2012 Presidential Election Poll (CPEP) is conducted within the American Life Panel, which is an internet panel recruited through traditional probability sampling to ensure representativeness. The CPEP differs from other polls in that it asks the same respondents repeatedly about their voting preferences. Thus, it leads to more stable outcomes and changes are due to individuals' changing their minds and not due to random sampling fluctuations. The CPEP is also different because it asks respondents to state their preferences for a candidate and the likelihood that they will vote in probabilistic terms (percent chance), which has been shown to improve forecasts several months before the election. This documents gives a detailed account of the methodology underlying the CPEP.
Kapteyn, Arie, Erik Meijer, and Bas Weerman, Methodology of the RAND Continuous 2012 Presidential Election Poll. Santa Monica, CA: RAND Corporation, 2014. https://www.rand.org/pubs/research_reports/RR858.html.
Kapteyn, Arie, Erik Meijer, and Bas Weerman, Methodology of the RAND Continuous 2012 Presidential Election Poll, Santa Monica, Calif.: RAND Corporation, RR-858-RC, 2014. As of May 12, 2022: https://www.rand.org/pubs/research_reports/RR858.html