American Association of Public Opinion Research
AAPOR’s Media Room has a number of handy guides on interpreting polling data, as well as information on how best to get in touch with one of the association’s polling experts.
The center formerly known as the National Opinion Research Center has a partnership with the Associated Press and is a good source for experts and data. The center has education experts, too.
While its education page isn’t always the most up-to-date, this site is a good, free resource for determining how public opinion has shifted on key issues over time.
This free, three-hour online course produced by AAPOR and Poynter takes you beyond the core concepts covered in this guide and can help transform you into the polling guru in your newsroom.