We’re just going through our next major design revision for Taptu, and it reminds me of just how important to us the whole topic of ‘click-distance’ is.

What is ‘click distance’? It is the sum of the number of clicks and the number of scroll actions that a mobile user must make when navigating to a specific item of content. It’s the critical measure of usability for mobile search.

Back in 2002, Professor Barry Smyth of University College Dublin carried out an experiment on the O2 mobile portal. For a sample of 150,000 users accessing the portal via the mobile browser, he measured their navigation behaviour. Specifically he measured the number of clicks and the number of scrolls that they would make on their phone keypads as they navigated the menu structure of the portal in their search for content. From this experiment came a very simple but incredibly important insight: the motivation of most users to continue navigating for content falls off a cliff when the click-distance exceeds 12.

Back at the end of 2005 we carried out our own research study into click-distance performance of mobile search engines. We asked a panel of users which 100 typical searches they would most like to do on a mobile phone, and which search words they would start with. We then selected the most popular mobile search engine, ran the 100 searches and measured the average click-distance. Shockingly, the average result was 36 clicks. It’s not hard to see why mobile search has yet to go mass market when you see a ‘usability gap’ of this magnitude.

When we design a mobile user interface for a device, or for a device family, the desire to minimise click-distance is always at the front of our minds. It’s become the central proposition of Taptu: how to deliver relevant mobile search results in 10 clicks or less. Needless to say, setting the objective of 10 clicks or less is the easy part. For a universal mobile search service, it is a very tough target.

We’ve just set up an internal research project to update our 2005 findings. This time around we have a lot more data on what mobile users actually search for, so our test database can be much more realistic. In the last couple of years, we’ve seen some improvement in the performance of the existing mobile search engines. We’ve also seen new kinds of devices like the iPhone which can do full Web search on a mobile using the desktop versions of popular search engines.

What effect will this have on click-distance performance for mobile search? Keep you posted.

This entry was posted on Friday, November 2nd, 2007 at 5:31 pm and is filed under Company News, Mobile devices. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.