Political science is a community enterprise; the community of empirical political scientists need access to the body of data necessary to replicate existing studies to understand, evaluate, and especially build on this work. Unfortunately, the norms we have in place now do not encourage, or in some cases even permit, this aim. Following are suggestions that would facilitate replication and are easy to implement -- by teachers, students, dissertation writers, graduate programs, authors, reviewers, funding agencies, and journal and book editors.
You may also be interested in Data Sharing and Replication. Also see related research.