A data broadcast network with a return channel providing a guaranteed error-free data delivery simultaneously to multiple receiving devices. The network transmits data in packets and uses the return channel for audience measurement and packets recovery. Whenever a corrupted packet is detected, the multiple receiving devices play a kind of "lottery game" running generators of random numbers, and only "winners" submit retransmission requests over the return channel. While in the game each receiver acts on its own, it is advised by the sender on the audience size, i.e. the overall number of receivers. It allows setting the game so to limit the number of retransmission requests to just a few and to keep it independent from the audience size. The sender performs the audience measurement by transmitting packets with wrong error-checking values and evaluating receivers' responses.