The agreement means Nielsen will move forward with its decision to implement continuous diary measurement in the 46 Nielsen Audio markets currently measured four times a year. The measurement will begin with a survey in July.

Nielsen Media Impact is a cross-platform media planning and optimisation tool offering insights on campaign reach, frequency and duplication using advanced audience segments.

Brad Kelly, managing director, Nielsen Audio, said: "The advancement of Continuous Diary Measurement in combination with Nielsen Media Impact will allow both buyers and sellers of radio to better evaluate, react, and adapt to marketplace changes. We are confident these tools will help level the playing field and bring radio’s attribution metrics on par with other media."

Greg Ashlock, president, iHeartMedia Markets Group, said: "Marketing mix models need fresh data to get a full understanding of how radio drives sales results and Continuous Diary Measurement enables better attribution with more current data in the larger diary markets. We also look forward to using Nielsen Media Impact to show clients how iHeartMedia substantially improves advertising results in optimised cross media campaigns."