The Noisy Channel


Clarification vs. Refinement

June 2nd, 2008 · 10 Comments · General

The other day, in between braving the Hulk and Spiderman rides at Endeca Discover ’08, I was chatting with Peter Morville about one of my favorite pet peeves in faceted search implementations: the confounding of clarification and refinement. To my delight, he posted about it at today.

What is the difference? I think it’s easiest to understand by thinking of a free-text search query as causing you to be dropped at some arbitrary point on a map. Our planet is sparsely populated, as pictured below, so most of the area of the map is off-road. Hence, if you’re dropped somewhere at random, you’re really in the middle of nowhere. Before you start trying to find nearby towns and attractions, your first task is to find a road.

How does this metaphor relate to clarification vs. refinement? Clarification is the process of finding the road, while refinement leverages the network of relationships in your content (i.e., the network of roads connecting towns and cities) to enable navigation and exploration.

“Did you mean…” is the prototypical example of clarification, while faceted navigation is the prototypical example of refinement. But it is important not to confuse the concrete user interfaces with their intentions. The key point, on which I’m glad to see Peter agrees, is that clarification, when needed, is a prerequisite for refinement, since it gets the user and the system on the same page. Refinement then allows the user to fully exploit the relationships in the data.

10 responses so far ↓

  • 1 Max // Jun 2, 2008 at 11:00 pm

    I completely agree that this is a very interesting topic. Its only recently come into my research path, but ive been thinking almost solely about it for the last few days. my concern is of the different ways that facets behave for each. but my question is – if a user is in refinement, does he need a special and more efficient set of interactions, or is he able to make efficient use of interactions with a clarification interaction model? i think this point is still to be tested… am i wrong?

  • 2 Daniel Tunkelang // Jun 3, 2008 at 7:02 am

    Here’s a simple but hopefully illustrative example:

    As part of my adjustment to married life, I’m updating my student apartment, and one of my top priorities is getting a new washer. So I head over to the Home Depot site and search for a washer. I’m all excited that they have washers for less than $50!

    Oops. Maybe I should have clarified (using the results of search against the facet values) before refining. I meant these washers. Guess I’ll have to pony up at least $200. But now I get to refine by meaningful facets, like color and capacity.

    Does that help illustrate the general principle? Of course, there are far more sophisticated ways to implement both clarification and refinement. My point here is to highlight the distinction, and to assert that clarification, when needed, should come before refinement.

  • 3 Pavel Serdyukov // Jun 3, 2008 at 10:26 am

    There is a good paper on this topic by Rosie Jones and friends:, where they distinguish these two types of reformulation, although they do not specify that one goes after another. This is indeed an intersting observation.

  • 4 Daniel Tunkelang // Jun 3, 2008 at 12:04 pm

    Interesting. I’d read that paper a while ago, but not in this light–probably because I tend to think about query reformulation in the context of faceted search and navigation. But I can certainly see the connection.

  • 5 Max Wilson’s Blog // Sep 20, 2008 at 11:47 am

    [...] an issue at the heart of many of our discussions on this blog: what is exploratory behavior? Is it clarification or refinement? Are users exploring in order to resolve imperfect communication with the information retrieval [...]

  • 6 Duck Duck Go! | The Noisy Channel // Oct 16, 2008 at 1:24 am

    [...] But Weinberg has truly done more with less. For example, when I do a query for SIGIR , I get a disambiguation dialog that bootstraps on Wikipedia. Yes, these are also the top two hits on Google, but with a dialog that implements clarification before refinement. [...]

  • 7 Faceted Search Presentation at New York CTO Club | The Noisy Channel // Dec 10, 2009 at 10:54 am

    [...] Facets get polluted with bad result sets, so offer clarification before refinement. [...]

  • 8 Blogs I Read: UXmatters | The Noisy Channel // Dec 20, 2009 at 8:19 pm

    [...] For example, in “Best Practices for Designing Faceted Search Filters“, Greg Nudelman offers a constructive critique of the Office Depot search user interface. Some of his material will be familiar to those who have read my faceted search book (particularly the chapter on front-end concerns), but the focus on a single example makes for a compelling read. I also liked Greg’s most recent post, entitled “Cameras, Music, and Mattresses: Designing Query Disambiguation Solutions for the Real World“. I was amused that he and I use the same “canonical” example for the need to offer clarification before refinement. [...]

  • 9 Designing faceted search: Getting the basics right (part 1) « Information Interaction // May 18, 2011 at 3:36 am

    [...] approach may be adopted. For example, a search on eBay using the query “golf” returns a query clarification dialogue as shown below: Facetes open for query disambiguation at [...]

  • 10 Designing Search (part 3): Keeping on track « Information Interaction // Mar 20, 2012 at 2:00 am

    [...] from providing inspiration, related searches can be used to help clarify an ambiguous query. For example, query on Bing for “apple” returns results associated mainly with the computer [...]

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