. A.C. Nielsen Sr. (1898-1980) A.C. Nielsen Co., Chicago List No. 69 of 100 Go to the Next Person of the Century Marketing's share-of-market concept began in 1923, when pioneering market researcher Nielsen's new company began checking food and drugstore shelves to tally product movement. His sales audits answered client questions about their marketing efforts, and as TV arrived Nielsen adapted his audit to deliver "the Nielsens," those influential audience totals for programs and commercials. A.C. Nielsen Co., as the world's largest marketing research organization, also conducted store audits and coupon-clearing services. Nielsen's new "cost-per-thousand" concept continues to influence decisions related to campaigns, media schedules, sales promotion programs, distribution patterns, entertainment and event production. All Rights Reserved © 1999 & 2005, Advertising Age Crain Communications, Inc. editor@AdAge.com .