Abstract: A device for estimating the general behavior of a group of persons, each son being the driver of a moving body. The invention relates to a device estimating comparatively the behaviors by measuring the average speeds of a same group or more generally of different groups in one location or at different locations. The device is comprised of a casing concealable inside an envelope including a display unit programmable by the threshold of the selected speed, and alternatively, two counters, one indicating the number of moving bodies exceeding the threshold value and the other counter indicating the total number of moving bodies. The components are a Doppler sensor, an amplification stage, a logic stage for the control of the counters, and a power source (i.e. batteries).