The volume and variety of data is so daunting that marketers often don't know what questions to ask or which metrics to use. We know we need to make sense of the growing mass of data, yet too often there's not enough method to our madness. Meanwhile, buyers travel their own winding paths to purchase across ever-changing e-commerce websites and social platforms, smartphones and tablets, and in-store visits - leaving even more digital breadcrumbs behind. What's measurable? Almost everything. What's meaningful? That's another question altogether.