Understanding How Users Search
Assuming you've decided to implement a searching system for your web site, it's important to understand how users really search before designing it. We'll try to condense decades of research and experience generated by the field of information retrieval into the next few paragraphs. But it really boils down to this point: searching systems can and should vary as much as browsing systems or any other components of web sites do, because all users aren't alike, and information retrieval is much harder than most people realize.
1. Users Have Different Kinds of Information Needs
Information scientists and librarians have been studying users' information finding habits for decades. Until recently, these studies usually pertained to traditional information systems, such as how to ask a library patron the right questions to learn their information needs, or how to make it easier to search for information in online library card catalogs or other databases.
Many studies indicated that users of information systems aren't members of a single-minded monolithic audience who want the same kinds of information delivered in the same ways. Some want just a little information, while others want detailed assessments of everything there is to know about a topic. Some want only the most accurate, highest quality information, while others don't care much about the reliability of the source. Some will wait for the results, while others need the information yesterday. Some are just plain happy to get any information at all, regardless of how much relevant stuff they're really missing. Users' needs and expectations vary widely, and so the information systems that serve them must recognize, distinguish, and accommodate these different needs.
To illustrate, let's look at one of these factors in greater detail: the variability in users' searching expectations.
1.1. Known-item searching
Some users' information needs are clearly defined and have a single, correct answer. When you check the newspaper to see how your stock in Amalgamated Shoelace and Aglet is doing (especially since the hostile Microsoft takeover attempt), you know exactly what you want, that the information exists, and where it can be found. This is the simplest type of information need. If it were the only type, the job of the web site architect would be much easier.
1.2 Existence searching
However, some users know what they want but don't know how to describe it or whether the answer exists at all. For example, you might want to buy shares in a particular type of mutual fund that invests in Moldovan high-tech start-ups and that carries no load. You are convinced that this sector is up-and-coming, but do Fidelity and Merrill Lynch know this as well? You might check their web sites, call a broker or two, or ask your in-the-know aunt. This kind of information need is more challenging: it might be hard to convey exactly what you're looking for ("Moldova? What's that?"), especially if it's a new and as-yet-unheard-of item. Rather than a clear question for which a right answer exists, you have an abstract idea or concept, and you don't know whether matching information exists. The success of your search depends as much upon the abilities of the brokers, the web sites, and your aunt to understand your idea and its context as whether the information (in this case, a particular mutual fund) exists.
1.3 Exploratory searching
Some users know how to phrase their question, but don't know exactly what they're hoping to find, and are really just exploring and trying to learn more. If you ever considered changing careers, you know what we mean: you're not sure that you definitely want to switch to a career in chinchilla farming, but you've heard it's the place to be, so you might informally ask a friend of a friend who has an uncle in the business. Or you call the public library to see if there's a book on the subject. Or you write to the Chinchilla Professionals' Association requesting more information. In any case, you are not sure exactly what you'll uncover, but you're willing to take the time to learn more. Like existence searching, you have not so much a question seeking an answer as much as an idea that you want to learn more about. Unlike the next type of searching, you don't need to know everything there is; a few pieces of good information will do fine for now.
1.4 Comprehensive searching (research)
Some users want everything available on a given topic. Scientific researchers, patent lawyers, doctoral students trying to find unique and original dissertation topics, and fans of any sort fit into this category. For example, if you idolize that late great music duo Milli Vanilli, you'll want to see everything that has anything to do with them - singles and records, bootlegs, concert tour posters, music videos, reviews, fan club information, paraphernalia, interviews, books, scholarly articles, and record-burning schedules. Even casual mentions of the band, such as someone's incoherent ramblings in a web page or Usenet newsgroup, are fair game if you're seeking all there is to know about Milli Vanilli. So you might turn to all sorts of information sources for help: friends, the library, bookstores, music stores, radio call-in shows, Ouija boards, and so on.
There are many other ways of classifying information needs, but the important thing to remember is that not all users are looking for the same thing. Ideally, you should anticipate the most common types of needs that your site's users will have and ensure that these needs are met. Minimally, you should give some thought to the variations and try to design a search interface that is flexible in responding to them.
2. Searching and Browsing Are Integrated
One drawback to the literature on information finding is that much of it deals with testing and improving a single information system (e.g., an online card catalog). But the truth is that most people, especially those with more involved information needs, use many information systems for a particular search. This often means jumping from Infoseek to Magellan to a specific site to Hotbot and so on, all in the context of one search. Even when using a single web site, users often alternate between browsing and searching. For example, when you use Yahoo!, you might first perform a search, find a useful site, and then, using its Yahoo! category, browse for similarly indexed sites.
3. Multiple Iterations Are Commonplace
Additionally, information searching generally doesn't take place within one clean pass, unless it's of the known-item searching variety. Information searching and browsing are by nature iterat ive : users will make a first attempt at finding information, learn something, refine their query, try finding some more, learn some more, refine again. This is commonly known as associative learning . Unfortunately, finding everything you need at once doesn't happen all that often, because you don't generally know enough about the topic to articulate your query the right way in the first place.
4. The Moving Target: A Likely Scenario
A typical example of a search for information might go something like this:
Jan, a budding entrepreneur, wants to get business cards printed for her new company. She calls her pal Fred to see how he did it and what company he used. Unfortunately, Fred is not in, and, never one to dawdle, Jan leaves Fred voice mail and moves on to the yellow pages. She finds nothing under Business Cards, but does see a number of companies listed under Printers, and gets a few price quotes, which all seem to be in the same neighborhood. Not sure which to select, Jan contacts the local chapter of the Better Business Bureau for their recommendation. The BBB folks refer Jan to their web site, where she can search a database of companies with dubious histories. This provides Jan with useful information that helps whittle down her list of candidate printers. Meanwhile, Fred calls Jan back and tells her that she really shouldn't have just business cards printed, but that she should hire a graphic designer to create a full graphic identity package for Jan's new business, including letterhead, brochures, and so on. So, Jan realizes that she needs to find an affordable, reputable graphic design firm, and she returns to the yellow pages. She also goes to the library to do a catalog search to see if any books describe what it's like to work with a graphic design firm, and how much she ought to expect to pay. And so on...
As you can see, Jan's initially simple information need becomes a fully fledged associative learning process, changing at least twice (from a hunt for a printer to a hunt for a graphic design firm to information on negotiating and working with a graphic designer), and for all we know, it's not over yet. It also involves multiple information sources (Fred, the yellow pages, the library catalog, the bookstore), and utilizes browsing (the yellow pages directory), searching (the Web database, the library catalog), and even asking (Fred, the Better Business Bureau). Things aren't always as simple as they seem! Your challenge, of course, is to design your site's architecture to support the most common searching and browsing approaches in a smooth and integrated way.