An introduction to sampling/monitoring networks

Sampling design is a critical part of any study involving modeling and estimation based on data that is sampled from natural resources or other phenomena occurring in the landscape. Statistical considerations related to sampling are part of a larger scenario involving theoretical knowledge, previously detected behavior and patterns of the phenomenon, costs, accessibility to sample sites, politics, and so forth. Thus, the sampling design algorithm should be flexible enough to accommodate external considerations in the design.

Currently, ArcGIS offers some methods to construct sampling designs:

Other types of designs can be relatively easily generated using simple scripts or models:

These methods do not easily account for variations in the probability of a site to be selected (other than splitting the study area into strata, which usually requires manual inspection of the study site and good knowledge of the process under study). Also, not all of them guarantee that the sampling design will be spatially balanced (that is, that the design will sample the entire population, due to the inherent randomness of selecting a site to sample). Due to this, the Create Spatially Balanced Points tool exists within the Geostatistical Analyst toolbox. An explanation of how this tool works and the publications it is based on can be found here: How Create Spatially Balanced Points works.

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9/11/2013