New article in Cybermetrics

Isidro F. Aguillo isidro at CINDOC.CSIC.ES
Fri Dec 17 12:32:12 EST 1999

Search Engine Results over Time - A Case Study on Search Engine
Cybermetrics, Vol. 2/3 (1998/9). Issue 1. December 1999
Judit Bar-Ilan (School of Library, Archive and Information Studies. The
Hebrew University of Jerusalem Jerusalem, 91904, Israel)
judit at


This paper examines the performance of search engines over time. The
performance is not as expected: search engines loose information,
relevant URLs that were retrieved at a given time by a certain search
engine, were not retrieved by the same search engine at a later time,
although they continued to exist and to be relevant. A closer
examination of the these URLs revealed that not only URLs were dropped,
but content was also lost for a large portion of these URLs: no other
URL retrieved by the search engine contained the same information. As
far as we know this aspect of the performance of search engines has not
been thoroughly studied before. The problem is investigated through a
case study, using the search phrase  "informetrics OR informetric". The
searches were carried out in one month intervals during a five months
period between January and June 1998. An additional search round and
comparison were carried out on June 1999. The six largest search engines
at the time were examined.

Isidro F. AGUILLO                  isidro at
CINDOC-CSIC                        Tel: +34-91-563.54.82
Joaquin Costa, 22                  Fax: +34-91-564.26.44
28002 Madrid. ESPAÑA/SPAIN
Programas Europeos (
Editor Cybermetrics (
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