A computer-implemented transmission scheme is provided to control client-server interchanges within a distributed communications network, such as a real time opinion research system. Interchanges include transmitting media streams between one or more clients to a server over a network. Periodic interchanges can be simultaneously or staggeredly transmitted to a sampling pool of active clients. A transmission mode unit implements the transmission scheme. A parameter selector establishes the transmission interval and transmission period used to trigger each interchange. A client assignor creates one or more sampling classes from the sampling pool by applying a sampling quotient generated by the parameter selector. A schedule editor produces a transmission schedule for the active clients. If more than one sampling class has been created, each sampling class would receive a separate transmission schedule for providing staggered transmissions at designated transmission intervals. The transmission schedule can include other data preparation and formatting instructions for compression, aggregation and packetization.