For decades the billboard and TV industries have tested markets in a way ecommerce entrepreneurs will find tell them a whole lot more.

Consider the consumer who may have seen 10 digital ads before purchasing -- by measuring clicks, you can't definitively attribute 100 percent of credit any one of those individual ads.

Multi-touch attribution -- an alternative to “last click” that awards value to each digital ad a consumer sees -- is an advertiser’s dream.

While digital advertising may be a quantum leap over traditional mediums (because marketers can target with precision who they want to see their campaigns) lift measurements are one case in which TV and billboard advertising had it right.

When applied to traditional offline advertising, the preferred RCT is a geographic lift measurement, in which one regional area is put in a treatment group and shown TV commercials or billboard ads.

Meanwhile, a similar regional area acts as a holdout or control group and isn’t shown any advertising.

The text above is a summary, you can read full article here.