A sample which has been selected by a method of random selection as contracted with one chosen by some method of purposive selection (ISI). Random sampling allows each element of the target population (as represented by the frame) a positive chance of being selected in the sample. This likelihood of being selected is the inclusion probability (or inclusion density for continuous populations); its inverse is the sample weight.
In this "Salmon Monitoring Advisor" web site, we use the term "reference site" to be synonymous with "control". That is, a reference site is a spatial/temporal location that is similar (ideally identical) to another site that only differs from the reference site by being affected to a greater (or lesser) extent by some mechanism that affects salmon. Of course, no two sites can be identical, but the careful choice of one or more reference sites will permit reasonably rigorous conclusions about differences in responses at those sites to the causal mechanism. More information on reference and control sites and the different uses of these terms can be found in Downes et al. (2002, page 122) and Roni et al. (2005, page 22).
Resilience is the term used to describe the extent to which an ecological system responds to disturbances without substantially changing its structure and function (Holling 1972). For instance, imagine two lakes, one that includes only a small number of species and/or functional groups of phytoplankton, zooplankton, and fish, and another thathas multiple species and/or functional groups in each of those categories. The simple lake ecosystem will probably be less able to maintain its previous structure and function after major disturbances such as massive nutrient loading, warming, or changes in seasonal timing of events than the second lake. An often-forgotten second component to the resilience concept that Holling (1972) described is that frequent disturbances help select for characteristics among component populations that lead to greater resilience.
Response designs are the descriptions of how the measurements will be made in the field and how the measurements will be summarized into intermediate results (i.e., what we call metrics in our STRIDE nomenclature).
Random sample
