Purpose Of The Dietary Exchange How Can I Control Who Answers My Online-created Surveys?

How can I control who answers my online-created surveys? - purpose of the dietary exchange

For the purposes of medical research I'm doing an online poll for the daily evaluation of hypertension and dietary habits. However, you must make sure that once someone has replied to my question is, he or she is not able to find them. Where can I find a site or downloading software to ensure that the polls do not react with the same IP / cookie?