Proving that marketing works will continue to be a challenge for businesses and advertising agencies this year, according to the worldwide chair and chief executive of ad agency Ogilvy.
John Seifert was speaking to CNBC's Karen Tso at the World Economic Forum (WEF) in Davos, Switzerland, on Thursday.
When asked about whether issues such as ads being seen next to inappropriate online content and the "viewability" of ads had been resolved, he said: "I'm not sure any of them have been resolved. I think they are all of a theme, which there is just a new expectation of accountability. Business leaders are under more pressure than ever to justify the investments they make, the expenses they authorize on behalf of clients."
"In the area of marketing, one of the most challenging parts of our job right now is validating that the spending that our clients are doing creates results that really matter for their business," he added.