David Brady is a Davies Family Senior Fellow at the Hoover Institution; the Bowen H. and Janice Arthur McCoy Professor of Political Science and Leadership Values in the Stanford Graduate School of Business; and a professor of political science at Stanford. Douglas Rivers is a senior fellow at the Hoover Institution and a professor of political science at Stanford University. An expert on survey research, he is also chief scientist for YouGov PLC, an international, Internet-based polling firm. Brady and Rivers discuss polling and how to measure change over time. With their current policy initiative they can poll the same individuals over time, which menas we know a lot more about them and, it is hoped, our society as they move from time one to time two. They also discourse on what the polls and policies get wrong and how the transformations and instability of countries affect the polls and policy.