Location-based Search: An Introduction

Location based search could loosely be defined as the ability to retrieve online information in relation to its proximity to a geographical location. It is simple yet very powerful tool to pinpoint information based on its location matching it with a search term.

A location-based search engine would naturally look at two aspects while trying to retrieve information from the web:

• Search Term: Here search terms will usually be related to something you are searching for locally. These search terms indicate mostly a service, a business or place like a restaurant or business. So one would either search for "information management" services in Atlanta, GA (very specific to business/service context), or, one would obviously look for hotels, doctors, escort services, etc. It is important note these keywords are talking more about specific entities rather than abstract entities. A workable location based search engine will understand this differntiation. However, location based search need not be limited to non-abstract terms.




• Geographic Location: Here the geographic location could potentially refer to many contexts: it could either be the location of the owner of the web page, mapped through the whois database; location mentioned in the address given on the page(e.g, an address of a business set up); location name that occurs anywhere on the page. In order to show the more relevant searches first, the search engine might have to rank the searches in terms of its precision based on importance given to one or more types of location contexts vis-a-vis number of occurrences in the search results.

Overture Local Search Demo, Yahoo!'s City Guides and Google Location Search: A Comparison

A quick study of the offerings suggests that most of the news stories while comparing Overture Local Search (demo search for lawyers in California CA) to Google Search by Location, were not comparing apples to apples. Google Search by Location and Yahoo!'s City Guides might stand some chance of comparison but again, here too, there are quite a few differences.

Overture Local Search Demo : Mainly this demo seems to be an engine to serve related local advertising. As far as search results are concerned, it is very difficult to distinguish this demo from SmartPages or SuperPages or any other online yellow pages for that matter. All the search results, except for the paid listings, consist of addresses and phone numbers connected to an interactive map. So basically no hyperlinks to actual WebPages.

Yahoo!' Get Local City Guide (Powered by CitySearch) : Very similar to a much more evolved online yellow pages with very extensive and detailed listings including many other features, such as distance (from the city center), rating, overview of the business, maps, etc. Most of the listings seem to be reviewed by editors and link to web-pages if any.

Google Location Search : In true Google-style - style that very often represents a spirit of non-commercialism yet in the end turns this non-commercial attitude into a business proposition - Google Location Search is at least an attempt to provide a geospatial information retrieval solution rather than just providing a paid directory listing (not that a paid directory listing any less useful). It tries to do something we discussed earlier - matching the search term to the location context of the WebPages. And that is where it also fails as well, many of the pages that we surveyed contained just one or two occurrences of the location, so it even lists a page that has multiple addresses as a valid result for a singular location.

Conclusion

All of these examples enumerated about only show that geography based search engines have a long way to traverse. The paradox here seems to be that if you go the Google way you are restricted in your ability to be precise (low precision), on the other hand if you go the directory way then you are not providing a genuine web retrieval engine(low recall or restricted recall), but you are providing an online yellow pages service. Nevertheless, these attempts at least tell us that these approaches to information retrieval are coming out of closets of academic research.