A research concern in Illinois, U.S.A., conducted a three - year study of the daily activities of some 3,000 people who were asked to keep ongoing records of how they were spending their time.
समूह में, १८ की उम्र से लेकर ९० की उम्र तक के लोग थे और इसमें अनेक पृष्ठभूमियों के लोग थे ।