**4.4. Repeatability and reproducibility**

The validation of assay performance characteristics comprises the determination of repeatability (intra-assay imprecision) and reproducibility (inter-assay imprecision). It is generally recommended to assay a few replicates from at least five samples within a single analytical run for repeatability and a few replicates from at least five samples in separate analytical runs for reproducibility [29]. For confirmation of good performance characteristics, CV% below 10% should be obtained for samples with more than 1% target PNH cells and below 20% for samples with minor clones (<1%).
