1. A method for assigning a survey to a respondent, the method comprising the steps of: generating a set of one or more screening questions; presenting the set of one or more screening questions to the respondent through a series of one or more digital messages transmitted over a network; receiving, over the network, input data in response to said respondent answering said set of one or more screening questions; and determining which electronic survey to present to said respondent, over said network, based on how said respondent answered said set of one or more screening questions.