How to conduct surveys using facebook?
This is just a few thoughts.

I agree with @adb that an obvious way to use facebook for conducting surveys is just to provide a link to an external website that runs the survey.

There is an interesting article by Tan and colleagues where they talk about using paid advertisements to get targeted participants on Facebook.  I thought the following statistics were interesting in highlighting the sheer scale required in order to convert an ad into completed surveys:  1.1 million ad impressions resulted in 280 clicks on the advertisement of which 59 responded to the survey of which 39 completed the survey.

References


Tan, H., Forgasz, H., Leder, G., &amp; McLeod, A. SURVEY RECRUITMENT USING FACEBOOK: THREE STUDIES. FULL TEXT