The company, which will be called Added Value, will be one of the largest operations within WPP's Kantar division, with offices in 21 locations. It will be headed by its global chief executive, Tamara Ingram, and the Diagnostic founder, Marc Agostini, who will become the non-executive chairman.
Added Value will aim to help clients make their brands desirable using new research techniques. It also plans to launch The Desire Index - an international study to measure the connection between desire, brands and consumers.
Ingram said: "Our new venture blends the skills and talent together to create a truly global, insight-driven marketing partner to solve clients' business and brand issues."