Last week I par­tic­i­pated in a web ana­lyt­ics panel at the Search Engine Strate­gies con­fer­ence in San Jose, Cal­i­for­nia. One of the audi­ence mem­bers asked why cam­paign data reported from their search engine didn’t align with data from their web ana­lyt­ics tool. For exam­ple, why would Google report 1,000 clicks for the key­word “ipod”, when the web ana­lyt­ics pack­age reports 800? Or why would Google report 800 clicks when the web ana­lyt­ics pack­age repors 1,000?

As some of you know, this isn’t a search engine mar­ket­ing phe­nom­e­non. Mar­keters that use email and ban­ner ads often see sim­i­lar dis­par­i­ties from those sys­tems and web analytics…

So what’s the deal? As I explained at SES, it is impor­tant to under­stand that these two sys­tems are mea­sur­ing fun­da­men­tally dif­fer­ent things and are affected by dif­fer­ent mea­sure­ment method­olo­gies. In the exam­ple above, Google is mea­sur­ing what I call pre-site activ­ity. Every time a key­word is clicked on Google​.com, Google reg­is­ters a click — irre­spec­tive of whether the vis­i­tor ever lands on the des­ti­na­tion web­site. By con­trast, the ana­lyt­ics pack­age mea­sures a click when the vis­i­tor *arrives* at the web­site itself. In other words, the web ana­lyt­ics pack­age is mea­sur­ing site-side activity.

This may seem like a minor dif­fer­ence, but it is not. Accord­ing to Google (and Yahoo) all key­word clicks are scru­ti­nized in sev­eral ways before they are reported by those sys­tems. For exam­ple, Google high­lights that they use “3 pow­er­ful tools for pro­tect­ing your clicks” — namely, detec­tion and fil­ter­ing, mon­i­tor­ing, and human exper­tise. If a click does not pass these thru these “tools”, it is not reported back to you — even if the vis­i­tor con­tin­ues suc­cess­fully to your site. Yet, to your web ana­lyt­ics pack­age, a click is a click. If a vis­i­tor arrives at your site from a key­word search, that click is recorded.

But that’s not all. Once on your site, if a vis­i­tor hits the Back but­ton, and then returns to your site again, that means 2 clicks in your ana­lyt­ics pack­age but only 1 in Google. Hit the Refresh but­ton, that’s another click in the ana­lyt­ics pack­age, but not in Google. Book­mark the land­ing page on the web­site and return via that book­mark, that’s another click in the ana­lyt­ics pack­age but not in Google.

By virtue of these two dif­fer­ent method­olo­gies, you can quickly get to wide dis­par­i­ties in key­word report­ing. At the cam­paign and ad group level this is much less obvi­ous than at the key­word level. I’ve seen any­where from 5%-90% dif­fer­ences in click report­ing from a search engine to a web ana­lyt­ics pack­age at the key­word level.

There are many other fac­tors that can also con­tribute to dif­fer­ences in report­ing. To max­i­mize your mar­ket­ing suc­cess, it is imper­a­tive that you under­stand these fac­tors and adjust for them accord­ingly. If you do not, you could eas­ily mis­in­ter­pret cam­paign per­for­mance and limit your mar­ket­ing ROI.

In my next blog, I’ll dis­cuss what you can actu­ally do to rec­on­cile these report­ing dif­fer­ences and max­i­mize your mar­ket­ing ROI.