Advertising expenditure data by media for the U.S. from 1935 to 2007 are publicly available mainly because of Robert J. Coen. In 1935, L.D.H. Weld, Director of Research for McCann-Erickson and formerly Professor of Business Administration, Sheffield Scientific School, Yale University, published advertising data in the magazine Printers’ Ink. Weld died in 1946. Robert J. Coen joined McCann-Erickson in 1948, just after he completed a Master’s Degree in mathematics. Coen took up compiling and publishing the advertising data in 1950. He continued compiling and publishing the advertising data through December, 2008.
The Coen advertising data are widely published and highly regarded. The data have been published in Printers’ Ink magazine, Tide Magazine, the U.S. Department of Commerce’s Survey of Current Business, the U.S. Census Bureau’s Statistical Abstracts and its Historical Statistics of the United States, Advertising Age, and various other publications under a variety of attributions. The Coen advertising data in aggregate are broadly consistent with government-produced advertising data. The Coen advertising data add to government advertising data insightful categorization of advertising expenditure by media.
The Coen advertising estimates are based mainly on private sources. In the mid-1950s, those sources were the American Newspaper Publishers Assocation, A. C. Nielson Company, Publishers’ Information Bureau, Farm Publication Reports, Inc., the Direct Mail Advertising Assocation, Angelo R. Venezian (a leader in the business-to-business trade press), Outdoor Advertising, Inc., and the Federal Communications Commission.  Without Robert J. Coen’s work within the advertising industry for sixty-one years, a long time-series of advertising expenditure by media almost surely would not be readily available. Most likely, most of the advertising data by media would have been lost forever.
One can easily imagine business reasons for not making data public. Data costs money to collect and maintain. Others shouldn’t be able to get it for free. Selling limited access to data can serve as a source of business revenue. Making data public might reveal some information that would be better not to reveal. If others gain access to the data, they might figure out how to compete more effectively with your business. Fear, uncertainty, and doubt can prompt organizations to do nothing, say nothing, share nothing.
Making data public can be a good business practice. Making data public enhances the credibility of data through widespread, independent review of it. Making data public can raise an organization’s business profile and foster its association with valuable knowledge. Making data public can further development of an industry. Making data public contributes to the stock of public knowledge that will endure and grow forever. That’s a noble project in which everyone can and should play a part.
Robert J. Coen, now 87 years old, recently stepped down from his post as an advertising forecasting director. Coen has been widely regarded as a leading advertising forecaster since at least the early 1980s. When Coen joined McCann-Erickson in 1948, it was the sixth largest advertising agency in the U.S. Interpublic Group, which evolved from McCann-Erickson, is now one of the big-four global advertising holding companies. Coen and McCann-Erickson have both succeeded in business and made a major contribution to public knowledge.
 Alter, Stewart (1994), Truth well told: McCann-Erickson and the pioneering of global advertising (McCann-Erickson Worldwide Publishers) p. 116.
 See source description in Historical statistics of the United States, colonial times to 1957, p. 516.