Here’s an 'Oldie but Goldie’ from the Kantar database.
An analysis of 1224 US online video ads showed that their impact varied MASSIVELY depending on the quality of the creative. This is consistent with findings from Nielsen and other highly respected sales modelling experts including Paul Dyson, Karl Weaver, Dr Grace Kite, Dr. Peter Cain.
What this graph shows is that the brand impact from advertising spend can vary by a factor of 5+. In other words, if your creative is strong, it can produce sales uplifts five times more than if your creative is weak. This is why obtaining consumer feedback on your advertising ideas and/or prototype executions can be so valuable, provided the feedback helps you optimise the content.