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Academic search engines

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Federated search engines

Federated search engines work on similar principles to metasearch engines in that they do not index the Web themselves, but rather search other search engines, web directories, databases and other parts of the invisible web. There are currently a number of federated search options (also called metasearch) for libraries, often linked in with other systems supporting electronic products and services, for example MetaLib (developed by Ex Libris as part of their suite of information management tools), WebFeat (used by more than half of the top US public libraries), MetaFind, ENCompass and CentralSearch.

This option is popular with libraries because of the ability to search multiple databases through one interface; the user can plug in a word or a phrase into a single search box and end up with a number of relevant results in a merged list.

Another advantage is that libraries can retain control of content, how the search is organized for the user, and to some extent the display of the results. Federated search tools are customizable so the library can incorporate their own catalogues and databases, creating a portal or gateway through which the user can access the full range of electronic holdings.

describes how the library portal/gateway is constructed by a combination of MetaLib and SFX, which together enable the user to:

  • find and use information resources to which they have access, such as databases, library catalogues, subject-based web gateways, e-journals, e-books, and selected Internet resources;
  • use a common interface to simultaneously cross-search these resources (up to ten at one time, where enabled by the supplier), then view and save results;
  • locate journal titles available in print or online and link to full text where available, via Get it! (context-sensitive linking).

The library will need to define the targets to be searched, what categories these fit into (usually subject related), and the "search" groupings, as well as design the interface. Metasearch tools may bring their own collections – MetaLib for example brings a selection of resources and databases which it claims are regularly updated. Vendors will therefore need to be notified of any subscription changes.

A major problem with databases is that to many students they are just names with little attached meaning, so an inexperienced user might end up looking for Jane Austen in Medline, for example. Many libraries provide subject guides to their collections, and federated search tools allow for databases to be grouped according to subject categories, and described in the way the library chooses.

Federated search tools are powered so that users can search over multiple databases, and either be linked directly to the search interface of the database, or receive results in a merged list.

Standards for search and retrieve in databases have been developed – for example, Z39.50 or NISO Metasearch XML Gateway – which make searching easier. MetaLib for example uses Z39.50, which enables it to bypass the database’s native search interface and use its own search system to retrieve and display results. However, it is only possible to search those databases which have also implemented Z39.50, and while more and more publishers are seeing the need for standards, not all are compliant. A federated search engine is only as good as the databases it searches: it may translate the search into something the native search engine understands, but it cannot improve on the latter’s search interface.

Additionally, federated search engines can only search citations, not full-text or abstracts, so that will be the basis of their relevancy ranking.

Another very useful feature is the ability to personalize searching by creating one’s own lists of resources, save and retrieve searches, and create preferences for the display of results: for example, MetaLib’s My Space.

Most federated search tools offer both a simple search option across the total range of databases (cross-searching), and also the opportunity to narrow the search by subject, database, or resource type. How these options work, and how they are described, varies according not only to the system but also its implementation, but here is an example from the Pennsylvania State University’s MetaLib (Figure 7), which offers:

  • A "quick search" where the user can do a single box search or a more advanced one with Boolean operators and the option of searching by title, subject, author, ISBN, ISSN or year.
  • A "multisearch" option where the user can select databases according to category.

Image - Figure 7. Screenshot of multisearch option in Pennsylvania State University's version of MetaLib.

Figure 7. Multisearch option in Pennsylvania State University’s version of MetaLib

Results from the "quick search" option are presented according to database, as shown in Figure 8 below:

Image - Figure 8. Screenshot of results from the 'quick search' option in Pennsylvania State University's MetaLib.

Figure 8. Results from the "quick search" option in Pennsylvania State University’s MetaLib

Exeter University Library uses MetaFind, which it is possible to access from an icon on the library catalogue page:

Image - Figure 9. Screenshot of MetaFind on the University of Exeter library's catalogue page.

Figure 9. MetaFind on the University of Exeter Library’s catalogue page

Users can search the library’s electronic databases and other resources via a simple search with options of keyword, title, author, or subject, or they can go to an advanced search option which allows them to search individual databases and use Boolean operators.

Central search has a series of different check boxes to help indicate the subject area underneath the search box, and it is possible to cluster results under date (the default option), author, article title, and database.

There are drawbacks to federated search: despite the unified search interface, they cannot compete with Google for speed, and they are also complex, which puts some students off. Haya et al. (2007), in their study of students using MetaLib and Google Scholar, found that benefits of metasearching were offset by the complexity of the tool. They also criticized the lack of standard search rules, and the fact that the back button did not work.

Another study of MetaLib, this time at Carnegie Mellon University and involving usability testing with students using thinkaloud protocols (George, 2008), also found students bemused by the complexity of the search processes. There was confusion about authentication, the SFX linking symbol, the cross-search (choosing databases) option, and navigation. The authors are particularly critical of the text-based navigation, proposing a more graphic approach for future versions.

Myhill (2007) reports on a large survey of the various library search and discovery tools at the University of Exeter Library, concluding that although their chosen system (MetaFind) received relatively high ratings for ease of use, the library still needed to do more to ensure that students could retrieve information easily and quickly, and without being deluged.

Another problem is that although the chore of individual search is avoided, results are ranked by database and therefore students need to be familiar with these. (Chen, 2007: p. 417, observes that in effect the trawl through databases is postponed from before to after the search.) Oberhelman (2006) describes how he conducted an experiment with his library’s newly implemented central search system. Mimicking the behaviour of a naïve user, he typed in the term "model", which has different connotations in different academic disciplines, into the search box, only to get a total of 678,664 hits! It is possible to refine that search by database – however this is only useful if one has some knowledge of what databases are relevant in one’s own area.

There are other issues related to databases – such as will the library’s authentication system be recognized when the user goes in via the federated search engine? Inevitably, too, different databases will return the same results, and duplication will become a problem.

Linking search with discovery

Users of search engines expect to be able to go straight to the object searched. Libraries are recognizing that it is much easier to discover and use resources when they are linked direct from the federated search, rather than the user having to go to another database. Link resolvers (for example, SFX, produced by the vendor of MetaLib, Discovery Resolver, Article Linker, and WebBridge) are tools that enable users to navigate direct to the resource. They are able to do this providing the link complies with OpenURL, which is a syntax for identifying content and creating web-transportable packages of metadata. OpenURL can link from OPACs and both bibliographic and full-text databases.