Posted December 28, 2009 12:17 pm by with 9 comments

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Earlier this month, Google announced that its Personalized Search results would come to even computers that weren’t signed in to Google accounts. With the opt-out system in place, many users and public computers can’t help but use personalized search by default—and it may be AdSense publishers paying for it.

The logic goes something like this: if Google is now storing information about what you’re searching for even if you’re not signed in, it may also serve ads based on your search and browsing history, which you’re less likely to click on than ads only relevant to the page’s content. I’m not 100% sure that theory holds true (need more data!), but at least some AdSense publishers are seeing definite drop-off since Google threw the switch.

A thread on WMW documents some of publishers seeing this problem—and others who haven’t. Among those who’ve spoken up, seven of eleven have seen some sort of decrease in December (the original poster cited a significant slide in CTR and clicks from December 5 versus prior years, with CTR down 12.3% to 22.6% of normal average and clicks down 22.8% to 35.2% of normal average).

Of course, the personalized search change isn’t the only explanation in the first 30 messages of the WMW thread, alternate explanations offered include:

  • the “Caffeine” update in Google’s index
  • annual holiday decline (though the OP and some others note that this is more significant than previous years)
  • the wider rollout of interest-based ads
  • short sample skewing the results
  • sector-specific slowdowns

Interestingly, the original poster returned the day after posting and noted that his CTR had jumped that day. He hadn’t seen a dropoff in his earnings per click (though the new high day carried much higher earnings).

What do you think? What could be behind a decrease—and have you seen one? Is personalized search affecting your AdSense results?

  • If it’s killing the Adsense publishers, then it’s killing Google itself too (much more than publishers).

    Google gets most of their revenue specifically through Adsense ads and if they drop off… Too bad for Google.

    So I guess, if that what you’re talking about is true… Google would definitely do their best to fix the problem.
    .-= Gennice´s last blog ..Make Windows XP Boot-Up Faster With A Quick Registry Tweak =-.

  • I have no way of knowing if personalized search is affecting my AdSense revenues but they are up (which is normal for this time of year). Take that for what it’s worth.
    .-= Michael Martinez´s last blog ..Keep blogging =-.

  • @Gennice—I believe more of their revenue comes from AdWords (on, since AdSense allegedly has lower CTRs than AdWords, though you’re right that long-term ill-effects for publishers wouldn’t be good. If it’s even happening, it could be an experiment—if they didn’t try it, they’d never know if they were leaving money on the table. (On the other hand, they also changed the definition of a valid click, making it much narrower—which means fewer clicks and less revenue, but probably better quality traffic for advertisers, so money isn’t the only factor.)

  • Kill one the golden gooses eggs? Doubtful. Protect it and make it make sense for all advertisers using it right? yes?

  • As a search user, personalization is a great thing. As a publisher, I’m really not sure what to think at this point. But I have to believe what is good for the customer is always good for the long term health of the business?
    .-= MNWBlogger´s last blog ..WordPress Blog Web Hosting =-.

  • Maybe I’m missing something but if Google are personalising the adsense ads that will make people more likely to click no?
    .-= kelvin newman´s last blog ..The 12 Internet Marketing Tools of Christmas – Internet Marketing Podcast Episode #56 =-.

    • Yeah, that’s why I’m not 100% sure the theory holds true and I’d need more data. At first glance, that’s what I’d think.

  • I’m seeing a huge downturn in CTR, CPC, and general traffic as a result of these changes…and they weren’t great to begin with. Google is shooting themselves in the foot and taking publishers with them. I am contemplating switching to Yahoo or Bing for publishing ads, but my main hesitation is loyalty…which I am not seeing from Google at the momment.

  • I’ve gotten into this discussion on forums before. A lot of the posting was tinfoil hat type stuff, but people really are worried about their positions dropping. Like I told them, if you have a site that people are clicking on, especially repeatedly it will probably help you. If someone repeatedly ignores your site, in that particular case you will lose some exposure.

    All in all, people were a bit panicked about what to do about all this, but it all goes back to just creating quality content and a usable site. This update really shouldn’t force you to change your technique.
    .-= Dan Abbamont´s last blog ..Just wrote a quick and dirty blog post finder =-.