Sampling Frame

Types Of Sampling Frames

Major categories of sampling frames are area frames for in-person interviews, random-digit dialing (RDD) frames for telephone survey samples, and a variety of lists used for all types of surveys. Few lists that are used as sampling frames were created specifically for that use. Exceptions are commercially available RDD frames.

The type of frame usually varies with the mode of interviewing, although many frames can be used for multiple modes. Some studies employ multiple frames, either because they use multiple modes of data collection, because no single frame has adequate coverage, or to facilitate oversampling of certain groups.

An in-person survey of households (or individuals living in households) may use multiple levels of frames: an area frame to select a sample of areas where interviews are conducted, and within the areas, lists of addresses compiled by field staff or obtained from commercial sources.

Telephone household surveys may employ RDD frames, directory-based frames, or a combination. Telephone surveys of businesses often use frames developed from telephone directories. Telephone surveys can also use as sampling frames lists from many sources, including government agencies, commercial vendors of lists, associations, and societies. Some of these lists are publicly available, and some can be used only when doing studies for the owner of the list. Examples of publicly available lists include lists of public school districts and schools maintained by the National Center for Education Statistics (there are also commercial frames of districts and schools) and lists of physicians maintained by the American Medical Association. Lists whose use is restricted include those of recipients of government assistance and customers of businesses.

Surveys conducted by regular mail or email often use as frames the same lists (mentioned in the [Page 791]previous paragraph) for telephone surveys. Web surveys could also use these lists as means to contact respondents via regular mail and request that they complete a questionnaire online. Another type of frame for Web surveys comprises one or more Web portals (Web sites that provide links to other Web sites).

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