Executives say email and search are the two marketing channels for which it is easiest to measure return on investment (ROI), according to recent research from Millward Brown.

The report was based on data from a survey of more than 300 senior leaders of brands, agencies, and media companies.

Online ads are seen as having the third-easiest ROI measurability after email and search. Direct mail ranks fourth.

Webinars are seen has having the hardest ROI measurability, followed by events/ conferences and content marketing.

Some 74% of executives say they would increase spend on digital channels if it were easier to track ROI; 71% say they would increase cross-channel spend if ROI measurement were easier.

About the research: The report was based on data from a survey of more than 300 senior leaders of brands, agencies, and media companies.