88 Kellogg Insight as a brand, incorporate this ambiguity into your decision-making? This is where your own intuition and instinct come in. But by virtue of what you know about how your customers behave and how the channel behaves and who is going to see the campaign or not—data you should be able to get—you can have a sense of what might work. You will also be able to look at outcomes after the fact. Do you see a bump in your busi - ness from the right channel? Still, now you have to weigh, say, a guaranteed 20 percent return from a digital campaign against something that you think was positive but could be more or could be less. That’s why, in the end, people diver - sify their allocations, because they know they need to take a portfolio approach. Marketing spending is essentially a portfolio-optimization problem, except it’s in some ways harder than finance, because we can’t always measure the return even after the fact. INSIGHT: How will advances in machine learning change digital advertising? GORDON: Machine learning has already changed advertising by improv - ing predictions about how someone will respond to an ad. Machine learn - ing is very, very good at problems where you have lots of information and are trying to make a prediction, such as, will someone click on an ad if I show it to them. And machine learning is very good about doing this quickly and on a large scale. So it is already part of the plumbing now in a lot of digital-advertising campaigns, whether people know it or not. INSIGHT: Are there other trends marketing leaders should keep an eye on? GORDON: Absolutely. First is the emergence of other companies in the Based on insights from Brett Gordon