Abstract: A market research retail sales data collection system and method includes a plurality of cooperating retail stores, each having an in-store device for automatically collecting processing and storing market research data in a substantially totally passive or non-invasive manner with respect to the on-going operations of each retail store. Each in-store device detects, interprets, processes and stores data on a real-time basis with respect to retail sales transactions occuring in the retail store. However, each such in-store device does not interfere with or require the active participation of the in-store Point-Of-Sale (POS) scanners/registers, POS controller or store computer controlling the normal operations of the retail store. Periodically, each in-store device transmits the data it has collected through a bidirectional comunications network to a central site.