Although survey research is commonly used to investigate everything (“everyone asks everyone about everything” is the way I put it in my book, The Problem with Survey Research), thereby generating unreliable information about virtually everything) some researchers obtain reliable information by field experiments. For example, Meghan Busse and Florian Zettelmeyer ran field experiments to measure differences in treatment between men and women when they called auto repair shops. Many differences were identified. When you want to find out what’s really going on, don’t ask; instead, experiment. For a description of the Busse and Zettelmeyer experiments and their findings, click experiment.
Field experiments have been used with outstanding success in electoral campaigns. See, Sasha Issenberg, The Victory Lab.