DANSK DS/ISO 5667-20 PDF

This guide establishes important principles for dealing with the use of sample data for decision-making. The scope includes decisions based on the assessment of the confidence that water quality:
. meets targets and complies with thresholds
. has changed
. lies in a particular grade in a classification system.
This guide sets out basic requirements and illustrative methods that will be adequate in many decisions of this type and in 3.1 and 3.3. In other cases these methods will also serve as a preliminary look at the sensitivity of decisions to error. This guide does not cover the full range of statistical techniques.
The discipline of taking such decisions should place constraints on way thresholds and targets are expressed, and it should dictate the form and scale of sampling programmes. This guide aims also to provide general advice in these areas.
NOTE In the water industry, the term 'standard' is commonly used to indicate the value or limit of the parameter of interest. However, in this International Standard the term 'threshold' is used to avoid confusion with International Standards, regional Standards and other published documents.