Reflections from the River

Keyword in snippet increases click-throughs

Key message: Having the searched keyword in the search results snippet results in click-through rates 5 times higher than for search results that don’t have the keyword in the snippet. No similar effect was found for keywords in the search result title.

The entries on a search results page comprise a title, snippet and URL:

Search engine result for 'bbc' from Google

There has been lots of discussion within the SEO community about optimising use of the title tag, how to improve snippets using the meta description tag and, recently, about changes to Google’s presentation of the snippet in search results. What I cannot find discussed, however, is the effect of search keywords in the title and snippet on the click-through behaviour of searchers.

I collected data on 80 keywords that resulted in a total of over 14,000 visits from Google.co.uk search results pages to 3 web sites. The keywords ranked from position 1 to greater than position 20 on the results page(s) and the web sites were all successful retail sites selling goods direct to consumers. For each keyword, I recorded the number of visits attributed to that keyword from Google that was ‘non-paid’ during one week in April 2009 (from Google Analytics). I also recorded the search volume for each keyword reported in Google’s External Keyword Tool (set for the UK and reporting search volumes for March 2009). Dividing visits by estimated search volume gave me an estimated click-through rate for each keyword.  I then gave a simple score for the presence of keywords in the title and snippet of each search result (for the 80 keywords going to one of the 3 sites).

The first result shows that the presence of keywords in the title of the search result has no significant influence on the click-through rate of searchers (all differences p>0.05).

Effect of keyword in title on click-through rate from SERPs

By contrast, either partially or fully matching the searched keyword in the snippet significantly increases the click-through rate from the search result (p<0.01 for No vs Partial and No vs Yes).

Effect of keyword in snippet on click-through rate from SERPs

It is important to note that the y-axis on these graphs is a logarithmic scale - a log transformation was applied to normalise the distribution of data so that parametric tests would be valid. The increase in click-through between no keyword in the snippet and either partial or full keyword in the snippet is 550%! The 95th percentile confidence limits suggest that having the search keyword in the snippet increases click-through rate by between 268% and 1708%.

Making sense of these results

There are good reasons to expect that the presence of a searched keyword within a search result will increase click-through rate. Inattentional blindness is well established in perceptual psychology - people simply don’t see what they are not looking for. The most famous experimental proof of this is the ‘Gorillas in our Midst video‘ by Simons & Chabris. The video shows two teams of players (in black and white t-shirts) passing basketballs (one for each team) to one another. Experimental subjects were asked to watch the video and count the number of times the white team passed the ball. Whilst all subjects were able to do so successfully, surprisingly few of them noticed the person in a gorilla suit that walked into the middle of the screen beat their chest and walked off-screen. So, if I’m searching for a particular keyword, I might literally not see the results that do not have my keyword in it.   Evidence of the impact of inattentional blindness on online behaviour was demonstrated several years ago by Jared Spool of Interface Engineering Design. He gave people a goal to achieve in navigating through a web site. Their success in doing so correlated with the the presence on the home page of the trigger words they had formulated in their minds for achieving that goal.  So, the effect of keywords within search results increasing click-through rate makes sense.  What, at first glance, is more counter-intuitive is that keywords in the title have no effect but keywords in the snippet have a large effect.

The fact that the title is in a bigger font and positioned on top of the snippet might lead us to expect the opposite effect: that keywords in the title should have a bigger effect on click-throughs than keywords in the snippet. If the keyword was always found in the title, as might be expected because of the importance of title keywords for SEO, then keywords in the snippet would be the only differentiator of relevance for searchers. But this was not the case - in the sample of 80 keywords studied 20 had no keyword in the title and 17 had no keyword in the snippet. There would appear to be two possible explanations for the importance attributed to snippets by searchers: firstly, the greater amount of text presented in a snippet enables searchers to get a better understanding of the keyword in context and this, in turn provides a better estimate of the relevance of the search result. The second possible explanation relates to the fact that Google always uses the title of the indexed web page as the search result title, whereas the snippet is compiled in different ways to try to maximise its relevance - maybe searchers have learned (almost certainly sub-consciously or tacitly) that snippets are better indicators of relevance than titles.

Whatever the explanation, the evidence presented here suggests that SEO professionals should make every effort to get keywords into the snippets of their search results.