• by David Goetzl  @dgoetzl, March 14, 2012

A top Nielsen executive said the addition of Walmart data to its retail sales product will go back three years, allowing clients to make some year-over-year comparisons. The Walmart information is scheduled to go live some time in the second quarter.

Over the past decade, Walmart -- which accounts for perhaps one-quarter of the U.S. retail business -- has withheld its data from Nielsen’s system. Last summer, however, Nielsen inked a deal to add the Bentonville, Ark.-based company’s results.

“It represents a whole new view of the marketplace,” said Nielsen CFO Brian West at an investor event Monday.

West said Nielsen is poised to benefit from the launch. Since deals are in place with manufacturers and other clients that use its sales analytics service; it doesn’t need to persuade clients to sign up. “This isn’t we’ll hope they’ll buy it,” West said. “It’s already committed to.”

West said implementing the Walmart data into the system has been time-consuming for many reasons, including tracking it back for three years.

Asked why Walmart opted to participate, West said the company is “looking to be innovative and contemporary and trying to understand their business.”