U.S. Census Bureau Research
http://www.census.gov/
This site by the U.S. Census Bureau provides a wealth of measures and data that are used to track economic performance, budgets and forecasting data, housing, crime rates, the environment, and a variety of other public policy areas.

The Center for Disease Control and Prevention
http://www.cdc.gov/
This website provides reports of measures and data used to track communicable and non-communicable disease rates. It also allows the viewer to explore a variety of other measures relating to workplace safety, the environment, and global health care.

Research Methods Knowledge Base on Validity and Reliability
http://www.socialresearchmethods.net/kb/relandval.php
This source provides a discussion of the concepts of validity and reliability, offering students useful graphics for understanding how these terms affect the research process.

Research Methods Knowledge Base on Levels of Measurement
http://www.socialresearchmethods.net/kb/measlevl.php
This site explores the different levels of measurement that are associated with attributes of variables. It also provides examples of each, and allows students to explore the significance of measurement in the research process.