A new comparative study into the four major search engines has found that results delivered by all four for the same search terms can be very different, with very little overlap between them.

The study was carried out by researchers from Pennsylvania State University and Queensland University of Technology in April 2007 for Dogpile, a meta-search engine which delivers results from Google, Ask, Yahoo and Microsoft Live Search.

First page search results on the four search engines overlap by less than 1%, while just 3.6% of organic results for a given search term are the same across the four. At the time of the previous study, in 2005, this figure was 7%.

The study “Different Engines, Different Results: A Research Study by Dogpile.com” was conducted by researchers from Pennsylvania State University and Queensland University of Technology in April 2007.

Some stats from the study:

  • Only 0.6% of 776,435 first page results were the same across all four search engines.
  • 88.3% of results were unique to one search engine.
  • 8.9% of total results were shared by any two search engines, 2.2% of results were shared by three search engines.

The study found that most first page results were unique to a particular search engine:

  • 69.6% of Google’s were unique to Google, while the same figure for Yahoo was 79.4%, 80.1% for MSN, and 75% for Ask.

As well as organic results, paid links seldom overlap:

  • Only 4.6% of Yahoo and Google paid links overlap for any given query.
  • On 22.8 % of all searches, Google did not return a paid link whereas Yahoo returned one or more.
  • Yahoo did not display a paid link in 9.9% of searches where Google returned one or more.