Random vs. Listed Sample for Telephone Surveys - 09/04/10

For telephone surveys find out if your research vendor will use listed (phone book) sample: This is a less expensive approach as interviewers are always calling a working phone number. However, from 15% - 40% of numbers are unlisted, so any sample using listed phone numbers will leave out an important segment – largely composed of women. Exacting firms use random digit dial (RDD) sample; that is, phone numbers that are randomly generated.