ISO 17994:2004 defines an evaluation procedure for comparing two methods intended for the detection or quantification of the same target group or species of microorganisms.
ISO 17994:2004 provides the mathematical basis for the evaluation of the average relative performance of two methods against chosen criteria of equivalence.
Any two enumeration methods based on counts (of colonies or positive tubes) or any two detection methods (presence/absence methods) intended for the same purpose can be compared.
ISO 17994:2004 provides no solution to directly compare a quantitative method (colony count or MPN) with a detection method (P/A).
BS EN ISO 17994:2004 history
2014BS EN ISO 17994:2014 Water quality. Requirements for the comparison of the relative recovery of microorganisms by two quantitative method
2004BS EN ISO 17994:2004 Water quality. Criteria for establishing equivalence between microbiological methods