Selecting devices from which to receive data for adjusting the performance of a positioning system. The positioning system infers the location of the devices based on beacons observed by the devices. The performance of the positioning system is compared to performance targets. One or more of the devices are selected based on the comparison. Data collection from the devices is adjusted to affect performance of the positioning system (e.g., improved or reduced). For example, if the positioning system predicts positions poorly for a particular area, data collection from selected devices within the particular area may be increased.