Technique for correlating purchasing behavior of a consumer to advertisements

Advertisements and promotions to which a consumer has been exposed are monitored together with the subsequent purchasing behavior of that consumer. The information is combined to analyze whether and to what extent the advertisements and/or promotions influenced the consumer's purchases. Purchases are monitored by producing a machine readable record thereof with a store cash register. The consumer inserts this record into a home unit which stores this information. The home unit is also capable of issuing a reward to the consumer for cooperating. Also ,the advertising, promotion and/or purchase data is classified by the home unit into selected categories which can be accessed by a computer for further processing to provide, for example, certain test results of interest relatively quickly because only a portion of all the collected data needs to be analyzed.