Research Methods for Policy Analysis

In addition to these comprehensive sites, also check out some of the following books: 

Theory and Practice in Policy Analysis (Harvard Login)
Methods for Policy Research (Harvard Login)
Mixed Methods for Policy Research and Program Evaluation (Harvard Login)
Public Policy Analysis (Harvard Login)
Handbook of Public Policy Evaluation (Harvard Login)
Handbook of Practical Program Evaluation (Harvard Login)
Conducting Interpretive Policy Analysis (Harvard Login)
Communicating Social Science Research to Policy Makers (Harvard Login)
Public Policy in an Uncertain World (Harvard Login)