Degree of spatial variability of CBP levels in the system | Number of CBP data available for the distribution system under study | ||
---|---|---|---|
1 site/sub-system | > 1 site/sub-system | > 1 site/distribution system (but not sampling site in each sub-system) | |
High | Use of the sampling site in sub-system | The closest sampling site from the subject's residence | Determination of comparable sub-systems. Use of the sampling site located in sub-system with the most similar characteristics. |
Low | Use of the sampling site in sub-system | Average of all sampling sites or average of the two closest sites from the subject's residence | Similar to above or average of all sampling sites |