Adsense CTR Weirdness

By Deane Barker on September 28, 2005

About seven weeks ago, we had a significant server outage. We were down for about 12 hours, then up and down for 24 hours after that. For some reason, this outage seems to affected my Adsense click-through rate (CTR).

Adsense revenue dropped considerably after this outage — from $23 or $24 per day to $10 or $12. It’s since climbed back up to maybe $15 on an average day.

I initially thought was due to a traffic dip, though I couldn’t figure out how a server outage could cause traffic to still be down seven weeks later. But I was looking through the logs today when I realized something — traffic is back up to its pre-outage levels. It’s the CTR that’s dropped. The same number of ads are being delivered, it’s just that less people are clicking on them.

Look at this graph. This is my Adsense CTR from the beginning (without the actual numbers, per the Google Terms of Service). You can see where the CTR went way up when I took the borders off the ads in mid-March. Then you can see where the CTR just dropped like a stone. This drop happened at the exact time of our server troubles.

Could this be a coincidence? If so, weird. But still, why a sudden change in the ad quality, regardless if it correlated with our outage or not?

For the life of me, I can’t figure out why an outage would cause CTR to drop. In my mind, there’s only one thing that would cause this: less appealing ads (this includes the possibility of getting PSAs more often). But how would an outage cause a change in the quality of ads delivered to site?

I’m not so much worried about the loss of revenue as much as I’m just incredibly curious as to what could have caused this. Any ideas?

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  1. Is it possible that after the outage more people began using the RSS feeds since they are less sure that the site will be up?

  2. My guess is that Google is not serving the premium ads they were serving prior to the outage. If you have an extended outage or change your IP address, Google puts you back in low end ads and low pay outs. From my experience, things tend to go up in tiers. It takes between 20-30 days to get back to the middle tier. It takes a couple of months or more to get back to the top tier.

  3. Eaxctly the same happened with us; our server went down for about 18 hours & then a couple of hours later for 2 hours. After getting everything back online our traffic was back to normal levels within a day but CTR nosedived.

    I agree with Austin’s comment – the ads that were being served were of a far lesser quality after the server outage than those served before the outage. It took about 6 weeks to get the CTR back up to the normal level. I believe this was because the quality of ads got increasingly better-matched to the content being served.

  4. Yep. We switched colo’s and therfore switched IP’s. We averaged $28 per day for a month, then $62 for 3 weeks, and we have been averaging over $120 for the last 2 months. All of this was with the same number of ads shown per day.

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