“What is the point of brand valuations if those doing the valuing are so off target?” This was the question posed in an article by Marketing Week columnist Mark Ritson calling into question the validity of brand valuations. He found that the average brand valuation was just as likely to overstate a brand’s value by more than 500% than it was to get within 20% of the actual price paid.

Head to head: The article spawned a session at the recent Festival of Marketing during which three of the largest brand valuation firms joined Ritson on stage to defend the process. Michael Rocha, global director of brand valuation at Interbrand; Doreen Wang, global head of BrandZ at Millward Brown; and David Haigh, founder and CEO of Brand Finance argued their case for why there are such major differences in their valuations. All three experts said they can explain the differences in detail—but for clients’ ears only. They certainly were not going to reveal their techniques with competing valuation firms in the room.

The session was recorded, so check out the video.