POSITIONING PERFORMANCE

An apparatus obtains test data, which comprises radio samples with associated indications of reference locations. The apparatus estimates for each of a plurality of representations of a radio environment positions based on the radio samples of the test data and on the respective representation. Each representation has been generated based on a different selection of batches of fingerprint. Each fingerprint comprises a radio sample and an indication of a location of measurement. Each radio sample includes a characteristic of a radio signal transmitted by at least one beacon and an identification of the respective beacon. The apparatus determines for each representation a positioning performance by comparing the estimated positions with the reference locations. Based on the determined positioning performances, the apparatus determines whether any batch of fingerprints is to be excluded from further use and/or which representation is to be used as a valid representation of the radio environment.