AdSense Experiment : The Follow-Up

Way back in March, I conducted a little AdSense experiment to see which type of visitors (direct, coming from internal or external pages, or arriving from search engines) were most likely to click on ads. It turned out that internal visitors – that is, people coming from another page on the same site – were the ones most likely to peruse AdSense ads. This result was contrary to the popular assumption that search engine visitors are the most eager ad-clickers.

Does this unconventional conclusion remain true  in the long-term? Today I’m going to post a follow-up study that discusses just that. The long-term results were… different.

Newly Charted

As of today, the visitor segmentation script has collected 52 days’ worth of data. This is five times the duration of the previous experiment (which lasted just over a week), so the results presented below are presumably much more accurate that those I posted last time.

Without further ado, here’s the updated CTR chart :

Units hidden to comply with AdSense ToS.

The updated study shows that visitors arriving from external sites (except search engines) are those who yield highest click-through rate. In the previous analysis, this group occupied the second-to-last spot. Internal visitors, who were the previous “leaders” – if one may use that word to describe people very likely to click on Internet ads – now fall into the second place. Search engine visitors come third. Finally, direct visitors – i.e. people who arrive via browser bookmarks or by typing in the URL – are still the least likely to create advertising income.

Here’s a chart comparing the old and new results :

Darker shades represent the previous results, lighter ones – updated research.

Of course, we also need to consider eCPM. eCPM represents the average earnings per 1000 impressions. Again, I can’t show you the actual numbers due to AdSense rules, but this chart should give you a general idea of the relative financial value of various traffic sources :

Interestingly, this is pretty close to what we saw in the previous study – internal visitors generate the most valuable clicks. External and search visitors share the second spot, and direct traffic is the least valuable advertising-wise.

Here’s a comparison with the previous results :

The past is dark, the present light. Future not shown.


Despite the updated rankings, the overall conclusion is the same one I arrived to last time – on this site, the CTR of search, external and internal visitors is very close. Showing ads only to one kind of visitors wouldn’t make much sense.

Likewise, the main take-away for other AdSense users is still this : don’t rely blindly on stuff you read on a blog somewhere; test any suggested optimization techniques yourself.

I think that the fact that I got slightly different results this time only reinforces the validity of that advice 😉

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2 Responses to “AdSense Experiment : The Follow-Up”

  1. xentech says:

    The amount of days you ran the test over is pretty irrelevant, what kind of impression sample size is it based on?

  2. White Shadow says:

    Approximately 136 000 impressions.

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