What Are the Common Challenges Brands Face?

David Perry: What do you guys at work think are those common challenges brands face when trying to sort of better attribute effects to marketing tactics or channels? It's a really interesting question. And I think if for sort of look across the research we see in the conversations we have, there are probably two recurring themes that come out and describe those as incrementality and timescale. The second problem is understanding that what is most effective over a short period of time may not be the same as what's mosteffective over a long period of time.