The two companies had been working on the pilot project since early in 2005. Arbitron and Nielsen said in a joint statement: "Despite a promising level of interest, we did not secure sufficient client commitments to make Project Apollo a sustainable venture for our two companies.
"We are grateful to the companies, consultants and to the marketing and advertising agency executives of the seven Project Apollo steering committee members who helped us explore the cutting edge of media and marketing research," the statement continued.
Project Apollo was designed to be a single-source, national market research service based on Nielsen's Homescan technology for measuring consumer purchase behaviour.
It was created to combine with Arbitron's Portable People Meter system, measuring electronic media exposure.
Susan Whiting, executive vice-president of The Nielsen Company, said: "We have learned a great deal from Project Apollo, and am confident that this work will enable us to provide even higher levels of quality service to our clients."