Representativeness of the Tested Protocols

The representativeness is judged both on supply area level and for individual properties. Representativeness of the protocols (PROT) is assessed on the basis of the following parameters  

In summary, all tested sampling procedures show a linear relationship with the composite proportional sample, albeit that the correlation is poor. RDT and the 30-minute stagnation samples, 30MS1, 30MS2 and 30MSA show the best correlation R = 0.5-0.6). RDT however, generally seems to overestimate COMP (slope 1), whereas 30MS somewhat rmderestimates COMP (slope 1). FF clearly shows the poorest relationship to COMP = 0.29 and the slope is 0.57. 

Ratio between the tested protocols and the composite proportional sample 

The ratio between the result obtained by the tested protocol and the result of the composite proportional sample is another w to erqrress the representativeness of the sampling method. Before showing the results, the approach used is explained  

Ratio between PROP and COMP Ideally, the ratio between the lead values obtained by the tested protocol (PROT) and the composite proportional sample (COMP) should be unity, or at least constant over a wide concentration range. To determine the variation in the ratio between PROT and COMP, the average ratio is calculated over both the combined test areas (total, all results) and the individual test areas (A-K). The 95 % prediction range of the average ratio is  

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The 90-% prediction range of the tested protocols The predietion range of a protocol reflects the accuracy of that protocol in predicting the value of the composite proportional sample. Therefore, the 90-% prediction range is applied to assess the representativeness of the tested protocols. 

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