When working with statistics, aggregate data, and microdata, it is important to consider a number of factors:
The UCLA Data Archive's Tutorials provides excellent information about working with social science data, citing data sources, how to read codebooks, etc.
Visit the ATS Statistical Computing website for tutorials, online statistical publications, consulting, etc.
For more in-depth information about doing statistics research, visit the following subject guides:
Here are additional sources that contain statistical information. Some are freely available while others are licensed resources.