A thermostat, includes a housing and an occupancy sensor that is disposed within the housing and configured to detect physical presences of users within a responsive area of the occupancy sensor. The thermostat may also include a processing system that is disposed within the housing and in operative communication with the occupancy sensor. The processing system may be configured to determine, after a trial period, whether to activate an away-state feature by storing indications of how often the occupancy sensor detected physical presences during the trial period, computing an occupancy level for the trial period, comparing the occupancy level to a threshold criterion, determining whether sufficiently true indications of occupancy conditions were sensed by the occupancy sensor during the trial period, and enabling the away-state feature of the thermostat if it is determined that the sufficiently true indications of occupancy conditions were sensed during the trial period.