(This is originally a chapter from the book Efficient information searching on the web.)
Meta search services are search services that do searches in other search services in order to put together a hit list of their own. The meta search services often do searches in both search engines and directories. In many cases sponsored links are mixed into the hit list in an unclear way.
Some people mean that meta search services, or meta search engines as they are often called, is a variant of search engines. But for information seekers, the meta search services differ in several decisive ways from the search engines.
Important differences regarding:
- opportunities for advanced search possibilities
- where the links come from
- the way in which the hit list has been put together
- how commercial links are presented.
- Get advanced search possibilities
The meta search services generally don’t contain particularly advanced search possibilities. The searching can’t be limited at all as it can be in a common search engine. This depends upon the fact that the meta search service does searches in many different search engines and directories, and the meta search service doesn’t adapt its searches to the different search services to any great extent. Certain adaptation takes place, but largely the meta search service only mediates your search words to the other search services and collects the top results.
The origin of the links
The meta search services don’t have indexes of their own but use those of others. They send queries to several search engines and directories at the same time. The meta search service then puts together the reported results into a hit list of its own. More frequently now it’s shown where the links come from, but not always. It’s not at all certain that the meta search service does searches in the largest search engines such as Google, Yahoo! and Bing.
A problem with the meta search services is that as they search in common search services, such as Google och Yahoo!, they also bring in hits from search engines that use only bought hits. The ordinary hits are then mixed with the bought hits in the hit list of the meta search service without any indication.
The way the hit list is put together
Generally the meta search service brings in rather few hits from the search services in which it searches, 10-20 hits is common. So even if the search generates several hundreds of hits in an ordinary search engine, the meta search service will only present the first tens of hits. When the search service has received the results from the search, a simple list is created. The hits from the large search engines are often weighted higher than the hits from smaller, unknown search services. Sometimes the hit list shows where the hit comes from and which place it had in respective search engine. If the hit is found in the results from several search services it will be placed higher up in the hit list.
But the hit lists can have many different appearances. They can be compiled or separate, i.e. one for each search service that the meta search service uses for searching. Some services use advanced technique, such as automatic clustering or categorization of the documents. The links in the hit list are then also divided into different sub-groups, different clusters, to facilitate the finding of relevant links.
Duplicates are normally removed from the hit list, and many of the modern meta search services bring together the duplicates and give them a higher ranking as they are found in the results from several search services. But in older and simpler meta search services duplicates sometimes occur in the hit lists.
The meta search services bring in a maximum number of hits from the search services. They interrupt the searching in the search services after a certain amount of time to prevent the search time period from getting too long which is why the maximum number of hits from all individual search services is not always reached. Some meta search services allow for a certain extent of regulation of the number of hits from each search service and the maximum search time period.
How commercial links are presented
Sponsored links are in many cases mixed into the hit list in an unclear way.
In the Metacrawler (www.metacrawler.com) search shown below the hits 1, 2, 3, 5, 6 and 7 are sponsored links. At first sight this is easy to miss as the hits are numbered normally, an ordinary link and a regular text snippet below the link. But under that it says ”sponsored by” before the URL and the hit comes from ”Ads by Google”.
Fig. Searching in Metacrawler on ”cell phone”
Most meta search services are commercial and run by means of advertising revenues. The services without advertising are research projects, publicly funded services or services run as the marketing of a specific search technology.
Searching in meta search services
To bear in mind regarding meta search services
- Which search services does the meta search service use for its searches? Try to find a list or do a search and study the hit list.
- They often perform only simple searches, they don’t use any advanced search functions in the search engines.
- The number of hits from each search service is strictly limited (often 10-30 hits/search service).
Advantages with meta search services
- Useful when you only want a limited number of relevant hits.
- Good choice for obscure subjects.
- Suitable for testing when you don’t find what you’re looking for.
- Good for getting a survey of the things that exist on the Web in your subject.
- The hits in the hit list can be very relevant as they present the highest ranked hits in each search service used.
Disadvantages with meta search services
- Normally only simple queries, no advanced search possibilities.
- Often no field searching.
- Only gives the top hits in each search service, thus not representing the total results from any search service.
When is it suitable to use a meta search service?
- In the beginning of a search in an unfamiliar subject to get an idea of relevant search words and important resources.
- When you quickly want to get an overview of central Web pages in a subject.
- At searches with clearly delimited and exact queries.
- When you want a fast result on a simple or popular search using one or two search words.
- If you want to compare the query results between different search services quickly.
See Chapter 5 for further advice and suggestions regarding the choice of search service.
Different meta search services
Horizontal presentation of the hit list
Most search services present the results in a long vertical hit list, but some services present the results horizontally, in various sub-groups or clusters. This makes it easier for you as a seeker to zoom in on the aspects that are important to you.
The meta search service Clusty (www.clusty.com) groups the hits in different clusters. Through the clustered results different aspects of the search are rapidly obtained. To the left in the illustration below the different clusters for the search on “information seeking behavior” are shown. Out of the 187 hits 30 belong to the cluster ”Research” and 17 to ”Needs”. If you want to get at a particular aspect, you click on the link for the cluster and the hits will show up in the hit list.
Fig. Hit list on Clusty from a search on “information seeking behavior”.
In the ordinary hit list to the right you can see from which search services the link comes. In this example the first hit comes from Ask, Gigablast and Live (Bing). After the URL (the Web address) there is a nicety — ”show in clusters”— through which you can see in which clusters the hit is included. And you can choose “new window” and “preview”.
Graphic hit lists
Several meta search services present the hits in maps instead of in traditional lists.
Fig. KartOO’s chart with hits from a search on the ”Deep Web”.
Kartoo (www.kartoo.com) is a French meta search service that presents its hits graphically. The graphic presentation may be difficult to interpret in the beginning, but it can often give new aspects to the search. The hits are presented in different maps. Below to the right on the screen is a button, ”next map”, which leads to the next map.
Table of common meta search services
|Meta search service||Searches in the following search services||Special features|
|Clusty (Vivisimo) http://clusty.com||Bing (Live), Ask, Gigablast, Open Directory||Clusters the results.|
|Dogpile www.dogpile.com||Google, Yahoo!, Bing, Ask||All four large search engines.|
|Ixquick www.ixquick.com||Yahoo!, Bing (Live), Alltheweb, Altavista, Ask, Gigablast, Entireweb, Wikipedia||Erases personal search information. International phone directory.|
|Jux2 www.jux2.com||Google, Yahoo! and Bing (MSN)|
|Kartoo www.kartoo.com||“Uses the best search engines” (before: Yahoo!, Live, Ask, Exalead, Open Directory, Altavista, Alltheweb, etc.)||Graphic presentation. Possible to choose which search services Kartoo should use for searches. Anonymous search.|
|Mamma www.mamma.com||Yahoo!, Bing (Live), Ask (Ads by Google numbered in the hit lists!)||Video search. US Yellow Pages and White Pages.|
|MetaCrawler www.metacrawler.com||Google, Yahoo!, Bing (MSN), Ask, About (Ads by Google numbered in the hit lists!)||All four large search engines. Image-, sound- and video searches. US Yellow Pages and White Pages. Search tip-function: Are you looking for?|
|Surfwax www.surfwax.com||Alltheweb, Yahoo!, CNN News||Shows extracts from the hits.|