Sampling frame
The frame is the representation of the target resource used in the selection of the sample. For discrete populations, the frame is the list containing each population element, the list of lakes or streams in the region of interest, sometimes referred to as a "list frame". For continuous resources, such as stream networks, a digital map of the stream network is the usual form of the frame. Accurate representations of stream networks therefore become critical as they become the functional target population. A list, map or other specification of the units which define a population to be sampled. The frame may or may not contain information about the size or other supplementary information of the units, but should have enough details so that a unit, if included in the sample, may be located and taken up for enquiry (ISI). Also, under sampling frame: A list of all members of a population used as a basis for sampling. Without such a frame, or its equivalent, methods of sampling with assured properties such as unbiasedness are not available. The frame in effect defines the study population (ISI; Thompson, 1992)
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