ESTIMATING AND USING SAMPLING PRECISION IN SURVEYS OF TRACE CONSTITUENTS OF SOILS

Sampling variance and analytical variance have been estimated in a survey of concentrations of trace metals in soils from public gardens in an inner London borough. Robust analysis of variance was used for this purpose and found to be appropriate. The resulting statistics were used to define criteria that identified unusual measurements for the purpose of checking or further investigation. The statistics were further used to assess the analytical and sampling protocols in respect of their fitness for the task of producing data of appropriate quality, in the light of the variation in the concentrations among the various gardens. Criteria for this latter purpose were also suggested.