Methods and systems for measuring and gathering data relating to presence of individuals within commercial establishments, relating to usage of publications by those individuals, and relating to exposure to products by those individuals. Participants in one or more studies carry a portable monitor having...http://www.google.com.tw/patents/US8135606?utm_source=gb-gplus-share專利 US8135606 - Gathering data concerning publication usage and exposure to products and/or presence in commercial establishment
