About the Party Identification Database
The analysis of changes in party identification over time is based on a compilation of 279 surveys and over 450,000 interviews among the general public conducted by the Pew Research Center from January 1992 to December 2014. These surveys are combined into one large data file that can be sorted according to a range of demographic characteristics, with comparisons made across different time periods. Yearly totals are calculated by combining all surveys for the calendar year, with appropriate weights applied. The table below shows the number of surveys and interviews conducted each year as well as the margin of error for each yearly sample.