This guideline is dealing with the determination of statistical parameters required for the characterization of measurement methods with regard to the assessment of microbiological air pollutants, e.g. detection limit, determination limit, measurement uncertainty and overdispersion. These measurement methods are based on a cultural detection and enumeration of colony-forming units (CFU). The guideline mainly describes parameters to be determined during development of a method and provides the adequate means for an entire validation of the applied measurement method. Moreover, it supplies information on verification for the users of a corresponding standardized and validated method. Therefore, this guideline also serves as an aid for lab-internal quality assurance. This guideline also contains an Excel programme for evaluation of the described parameters in order to ease validation and verification.