Book: Search Patterns

2012-07-28 20:41
I got the book months ago during FOSDEM - the O'Reilly book table always is a pretty dangerous place as a meeting point for me: Search Patterns - Design for Discovery is one of those small, deceivingly beautiful books that manages to explain effective search engine design by focusing on the end user needs but going into some detail concerning the basics of search engine backends as well.

We use them on a daily basis not only for finding content on the web but also for navigating shopping sites, discovering news content and even finding articles on blogs and open source project pages. Many discovery tasks can be easily expressed as a search problem and as a result tackled with by now standard off the shelve software like Apache Lucene - or event the commercial counterparts from the enterprise search market. Still oftentimes search is perceived as being made up of simple a small box that users type (typically one or two term) queries into and that as a result show a list of some ten links.

After setting the stage for search in the first chapter the book goes into some more detail in "The anatomy of search". In a very approachable way it explains all the components from user constraints, graphical interface, the basics of retrieval and evaluating search performance in terms of precision and recall. The third chapter shows some bahavioural patterns that make discovery easier for users - from incrementally constructing the answer, progessively disclosing more and more detail up to being predictable.

Finally the design patterns as identified by the authors are introduced. Pretty obvious to those working in the field but well explained to those not intimately familiar with the topic:

  • Though perceived as a mere convenience to type less by users, autocomplete can actually help guide the user's search in case of ambiguities and can help avoid imprecise results.
  • Expected as it might be by users, presenting the best result first actually goes a long way when building credibility for a search engine. Having more precise queries to guide e.g. as a result of autocomplete helps here. So does having strong ranking criteria to build up a compelling ranking function that is used by default (even though others might be offered as an alternative for users to explore more and different results).
  • Federated search has both - advantages (integrating otherwise isolated silos of knowledge) but also disadvantages (it's speed being dominated by the slowest connected search engine).
  • Facetted navigation is pretty much standard for any major search engine - giving the user the option to start with a broad query that returns an overwhelming amount of results but guiding the user when refining the query is one major way of driving searches.
  • Offering personalisation tends to be one beloved feature though it is particularly hard to implement and needs a good deal of user data to work well. Usually there are features that require less work to get done that are more promising to start with.
  • Pageination is as much standard to be expected by users - though its implementation can differ: Though we are used to clicking the next button, this actually may not make much sense and just lead to interrupting the user's flow. Much more appealing - but sometimes also confusing - can be interfaces that allow for simply extending the result page when scroling to it's end.
  • Structured results provide a way to give the user more than just an outlink - triggered by specific searches it may be possible to directly answer the user's question instead of linking to content that answers it.
  • Actionable results are a way for the user to get active - either by voting on results, bookmarking them or sharing them with others.
  • Unified discovery is about accepting that search always plays a role in a bigger context and has to play well with the discovery mode the user is in: When searching for "apple" while browsing the category "electronics" it's rather unlikely that I am looking for the fruit. Similarly search should take context into account and support me seamlessly when switching from discovery to directed search and back to discovery mode.

The book concludes by going into some detail on example search engines and presenting some features that are not yet commonplace but might change the world by employing search in new and creative ways.

Easy to read, well written, several nice examples to make the technical points simpler to understand. Definitely a good read for domain experts planning to build a search engine, designers trying to understand the basics of building effective search engines and engineers struggling for words to explain why a seemingly little box can cause a whole lot of pain when done wrong but a whole lot of joy when done right.