Google Limits Referrer Data: What Marketers Must Know

Search engine optimization, landing page customization, and search retargeting will get harder because of changes Google is making to protect user privacy and security.
Google announced that it will begin rolling out default SSL (https) searching for users who are logged in to a Google account. When those users click on a search result to come to your site, you will no longer know what search term led them there. If the users click on a paid ad, the search referrer data will be passed on as before.
Here are Google's announcement and its brief notes on what the changes mean foranalytics and Webmaster tools. Search Engine Land has the most comprehensive overview of the effects on SEO. Danny Sullivan reports that the ACLU and the EFF applaud Google's announcement, but the SEO community loathes it.
How much of your traffic will this affect? It's hard to know for individual cases, but Google's Matt Cutts says we are talking about "single digits." Virante measured one site's traffic from logged-in Google users (using methodology that is difficult to implement and frowned upon by Google) over three months and found that the number was 11 percent.
Here are some of the effects you can expect from these changes in the data flowing from Google:

• Decreased accuracy in SEO and analytics. The CTO of Virante, Russ Jones, explains the possible impact of the loss of this much data:
  

  There are [probably] substantive differences between individuals who tend to be logged in and those who do not. Subsequently, conversion statistics generated from organic data in Google may misrepresent the actual behavior of your general user base because it neglects to include that 10 percent. This is especially important if that 10 percent proves to be a valuable, higher converting audience.

• Less effective landing page customization. When you know the search term by which a visitor found your site -- "washing machine," for example -- you may build a customized landing page offering links of interest to someone in the market for a washing machine. This will work for fewer visitors after Google's changes are fully rolled out.
• Search retargeting getting harder. This technique (described in detail here) lets advertisers serve relevant ads to those who have searched for a keyword of interest in the past. Google does not conduct search retargeting for its own ads (forcomplicated internal reasons), but it offers advertisers a workaround. Yahoo conducts a broad-brush form of retargeting and offers an advertiser product in this area. A number of ad networks also provide retargeting. To the degree that search referrer data goes away, all of these will be less effective.

Some question Google's wisdom (and perhaps motives) for the decision to continue passing search referrer data from paid ads while blocking it from organic search. Didit's Kevin Lee isquoted by Clickz: "Marketers who rely on search intent data to customize the usage experience of the Website or for remarketing purposes may find themselves having to rely more on paid search." And here is Virante's Russ Jones again:

The new referrer blocking change doesn't just discriminate against the SEO side of the search marketing family. It also sends a terrible signal to consumers. It says that referrer data is important enough to protect, but not important enough when advertiser interests are at stake.

Google's move is good news for user privacy, security, and relevant search results. But make no mistake -- it will have an impact on search marketing. The 10 percent of users who log in today will surely grow over time as Google rolls out more Google+ features and integrations. And Microsoft and Yahoo may yield to the privacy pressures that prompted Google to act. The ability to know what users searched for was nice while it lasted, but its days are numbered.
Please weigh in on our quick poll (over to the right there), and let us know what you think about the impact of these Google changes.
— Keith Dawson , Senior Editor, The CMO Site
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