Shopper Marketing metrics still need definition

Marketing Daily reported here on Shopper Marketing, with a few interesting points. The main one, to me, is this:

Only one-third of both retailers and manufacturers report that they agree on the metrics for evaluating programs even "most of the time," while nearly two-thirds of marketers say they only reach agreement with retailers about how to measure success "occasionally" or "never."

The metrics for Shopper Marketing are going to be difficult to define, and even more difficult to get agreement on, in part because it's both brand marketing and trade promo at the same time, and in part because the definition is still in flux -- how can you measure it if you can't define it? I addressed these points here.