Sampling Design: A Necessary First Step to Data Collection,
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB
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Since the assessment of water quality conditions of an entire water body must be based on the analysis of a relatively limited number of samples, it is extremely important that a statistically sound sampling design be established. Sampling designs are often inappropriate because of ambiguous objectives, inadequate knowledge about the system, or manpower and funding constraints. One successfully used technique for designing water quality monitoring programs involves the use of preliminary sampling or pilot studies. Pilot studies, while being expensive to conduct, can be effectively used to identify heterogeneities in reservoirs which then can be used to design less expensive, less intensive, statistically-sound long-term monitoring programs. The advantages of using an appropriate sampling design for water quality assessment given by Reckhow are 1 Sampling becomes more efficient. Samples are only collected if they reduce uncertainty thus, characteristics should not be sampled if uncertainty in their estimates cannot be reduced further within given budget constraints. 2 Sampling design stimulates thinking about the issue of concern, and leads to a better definition of informational needs. 3 Sampling design leads to an explicit quantification of the uncertainty in the estimates of the characteristics sampled.