• by Laurie Sullivan , Staff Writer @lauriesullivan, March 3, 2010

The flawed saying "if you can't measure it, it must not exist" took new meaning when Google began to request budget credit for visits on sites where AdWords serves up ads across the content network.

Now paid search and search engine optimization professionals have begun to pay more attention to the marketing funnel, too. Some urge clients when allocating ad budgets to consider pay-per-click (PPC) ads and query ranking much more than the last click.

Google late last year added a metric in AdWords called view-through conversions that, when pared with multiple exposure attribution, creates "a bit of controversy," though Clix Marketing Founder David Szetela believes it shines light on an important topic.

But while some advertisers want to know about prior site visits because eventually it could lead the visitor to make a purchase, others believe those site visits don't happen enough to consider them in the equation.

Even so, Szetela says traditional analytics don't measure a person's previous visits to a Web site, but marketers need to consider all contributions that lead to conversions. He points to actions prompted by paid search ads or SEO strategies resulting in the sale.

Google knows when someone visits a content site that contains ads it serves up, because the search engine drops a cookie in the browser as the Web site page loads. Szetela notes that if cookies aren't cleared from the browser and a week later the same person goes back to the Web site where ads appeared, clicks on a product and buys it, Google says AdWords deserves credit because it displayed an ad that influenced the consumer to buy the product.

Szetela, whose book (Pay-Per-Click Search Engine Marketing: An Hour a Day) scheduled for release soon, will highlight the strategy. He describes Google's formula like this: one view-through conversion equals one person who loads an ad page, doesn't click on the ad, but later found the ad on the advertiser's site through some other means, and completes the sale.

Should advertisers and marketers give credit to the site visit for the ultimate sale, or factor the site into the cost for conversion?

AdWords can become greedy and count the conversion if the person clicked on an ad at any stage in the conversion process, says Will Critchlow, cofounder of U.K.-based SEO firm Distilled.

"Some systems work on first touch, or 'greedy' attribution, whereby the conversion is attributed to the first way I heard about a site," Critchlow says. "This seems fairer, except it means you would never invest in tools like email marketing that are excellent at getting people to actually buy things."

There are several schools of though, Critchlow says. He describes most sophisticated models assigning some portion of the conversion to each of the touch points along the way. In other words, if someone visits the Web site five times before buying -- three times from different searches, once off a direct visit and once from an email campaign -- you might have a model that assigns 50% to the first touch, 30% to the last touch and a small portion of the remainder to the other touches.

Very few people actually do this, Critchlow says. "I believe some of the big brands work on sophisticated models to understand which bits of the funnel drive conversions," he says. "The whole thing becomes religious when you realize that you are talking about large budgets, and a switch from last touch to first touch attribution, for example, could mean a massive amount of money moving from one department's budget to another department's."

Critchlow says view-through conversions add a whole other layer of complexity, because the person may not actually have seen the advertisement. It could have been below the fold, for example. If a company advertises across many Web sites, the chance that someone will buy the product without seeing the ad remains high.