NEW YORK: Marketers are fully aware that current client-agency relationships face a series of challenges, ranging from transparency to more activities being taken in-house, but a new study has identified 40 strong relationships that have endured.

Consultancy firm R3 has released a guide to the best client-agency relationships after gathering more than 100 submissions from leading global marketers and their agencies.

Called Global 40, the study whittled down these submissions to a final 40 relationships that have stood the test of time and proven themselves to be effective and mutually beneficial.

Interestingly, R3 noted that the 40 relationships in its study have lasted for an average of 22 years, compared to the industry average of 3.2 years, proving that "managed pro-actively, these commitments can endure".

"Great marriages require mutual trust, a common understanding and clear goals," said Greg Paull, Principal of R3. "What separates these partnerships is a sense that both sides are working to improve brand outcomes, separate to personal agendas, politics and infighting," he added.

Some of the world's best-known brands are included in the rankings, including Procter & Gamble, the world's largest marketer, which has four relationships in the top 40.

R3 said that Procter & Gamble invests as much internal time on training its own team on agency management as it does immersing the agencies, but it also highlighted the successful multiple relationships developed by Unilever, P&G's great rival, as well as Coca-Cola and McDonald's.

Some of the other top brands featured in the report include Adidas, Apple, BMW, FedEx, IBM, Mondelez and 24 others.

Based on how these brands have maintained effective partnerships with their agencies, the study also drew six important conclusions for global CMOs.

"Look to new models" – R3 said all cases in its report had experimented with new ways of working, structures and outcomes.

"Face time matters" – despite the rise of technology, R3 said the best partnerships find ways to regularly connect to share best practice.

"Focus on outcomes, not inputs" – as with the recent agreement between McDonald's and Omnicom, both sides can align by setting mutually common objectives.

"Take digital seriously" – global CMOs need a strategic digital partner rather than one just for tactical execution.

"Immersion both ways" – both clients and agencies need to build understanding of each other's work and internal initiatives.

Finally, "Benchmark and evaluate" – global CMOS and agencies need to share a "Dashboard of Best Practice" to drive effectiveness and efficiencies.

Data sourced from R3; additional content by Warc staff