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SPATIALLY-BALANCED SAMPLING OF NATURAL RESOURCES IN THE PRESENCE OF FRAME IMPERFECTIONS
Citation:
Stevens, D. L. AND A R. Olsen. SPATIALLY-BALANCED SAMPLING OF NATURAL RESOURCES IN THE PRESENCE OF FRAME IMPERFECTIONS. Presented at Joint Statistical Meetings, Atlanta, GA, August 5-9, 2001.
Description:
The spatial distribution of a natural resource is an important consideration in designing an efficient survey or monitoring program for the resource. Generally, samples that are more or less evenly dispersed over the extent of the resource will be more efficient than simple random sampling. We review a unified strategy for selecting spatially-balanced probability samples of natural resources. The technique is based on creating a function that maps 2-dimensional space into 1-dimensional space, thereby defining an ordered spatial address. We use a restricted randomization to randomly order the addresses, and then apply a transformation that induces an equi-probable linear structure. Systematic sampling along the randomly-ordered linear structure is analogous to sampling a random tessellation of 2-dimensional space, and results in a spatially well-balanced random sample. An extension of the basic technique provides the ability to augment the sample after the fact. In this paper, we use simulation to investigate the ability of the augmented design to maintain spatial balance in the presence of non-sampleable points, either because of frame imperfections or access refusal.