What is "research"?
IRB review is not needed for all activities that employ social science methodologies. When you are planning to conduct a survey, or interview people, or otherwise gather or analyze information, this does not necessarily mean that you are conducting "research involving human subjects", as defined in the federal regulations, which use the following definitions:
"Research means a systematic investigation, including research development, testing and evaluation, designed to develop or contribute to generalizable knowledge. [45 CFR 46 102(d)].
"Human subject means a living individual about whom an investigator (whether professional or student) conducting research obtains (1) Data through intervention or interaction with the individual, or (2) Identifiable private information. [45 CFR 46 102(f)].
If your planned work is not "research involving human subjects", per these definitions, then it does not require IRB review under the regulations. In practice, determining whether an activity meets the criteria for "research involving human subjects" can be difficult. Moreover, some universities have policies whereby they require IRB review for projects beyond that strictly required by the regulations. The ultimate arbitrator of such matters is your university. (See the sections on university policies on applying the criteria and university policies on the need for IRB review of class assignments for examples of policies that have been adopted by various institutions.)
Applying the criteria for "research involving human subjects"
In some instances, a proposed activity will clearly meet the criteria, and an IRB review will be in order. In other cases, the criteria will clearly not be met and the activity will not require IRB review, under the regulations. In the latter case, not needing to undergo review doesn't mean that you can ignore ethical considerations in your work. On the contrary, the work must be conducted in a fashion that meets professional ethical standards (see the Professional Ethics section of this website for details).
University policies on applying the criteria
Absent federal guidance on applying the criteria, some universities have developed written policies that help faculty make a determination about the need for review.
Rutgers' policy relies on vignettes, which may be harder to apply to specific cases.
Again, these are examples; you should consult with your own institution regarding local policy.
Expert recommendations on applying the criteria
Pritchard, IA. Searching for "Research Involving Human Subjects: What is examined? What is exempt? What is exasperating?" IRB: Ethics and Human Research 23(3):5-12, 2001.
This piece, written by a current OHRP staffer, also provides a good orientation to the question of what constitutes "research involving human subjects."
Frequently Asked Questions and Vignettes: Interpreting the Common Rule for the Protection of Human Subjects for Behavioral and Social Science Research
The National Science Foundation, Office of Budget, Finance and Award Management has posted this very helpful and concrete guide to their thinking. You should be aware that it only applies to NSF-funded research, technically.
This document from the Center for Disease Control draws the distinction between public health "research" and "non-research". Again, this technically applies only to the work that it funds, but it is a useful frame to thinking about the issues.