Why Do Google Hit Numbers Vary?

Supa-Fly writes "I have a question about some conflicting results with the search engine google. I did a search for "pictures of mountains" and got exactly 1 million results. My friend did the same search (from the same office)and got 1,010,000 results. A second friend did the same search as the last 2 and got 1,020,000. These have not changed and every person gets the same results each time. My question is what is up with the discrepancies on google's search results?" Since this question is hard to answer from the outside, Craig Silverstein of Google kindly supplies his best answer to this question, below.

Craig writes: "Thanks for the great question. We get this from time to time and hopefully I can clear up some of the confusion. The number of estimated pages listed to the top right of a Google search results page is indeed, an estimate. It's a good estimate but still, an estimate.

There are many reasons why one might see a difference in the estimated number of pages returned for the same query. It's most likely the queries made by your co-workers were sent to different Google datacenters in what appears to have been a round-robin fashion. The index at any given Google datacenter can change slightly over the course of a day (each index is refreshed completely every three to four weeks). Depending on which datacenter finishes a query, the estimated number of results may vary.

Without having direct access to your environment it is hard for me to tell for sure, however, I believe this is the case."

Comments

wow, could we all have missed this?

[Tiber]

About a month ago, someone posted this story over on K5 regarding the google dance. Good to see it's run by a marketing site, I couldn't think of anyone who might have more of an interest in rankings then those bastards. :P

Re:number oddities

[millette]

Actually, if you use an uppercase OR, it will perform a boolean search. Otherwise, the search defaults to an AND, unless of course you're using doublequotes "like this" to search for a phrase.

Google Dance

[kiwirob]

Results can also vary due to the Google Dance.

Google has 7 data centers each with a copy of it's index and these are "usually" mapped to www.google.com. But google also has versions located at www2.google.com and www3.google.com.

During the monthly update there can be different version of the index on each of the 3 versions. A website www.google-dance-tool.1hut.com provides results for a search done on all 3 of googles index.

To check to see if the google dance is happening the most common technique is to check the "back links" for mayor sites like Yahoo by typing "link:www.yahoo.com" into the search box. this will list all the sites with links to "www.yahoo.com".

The Google Dance Tool site mentioned checks google every 5 minutes to see if the dance is on. Once it is started it sends out an automated email to subscribers (like me) so I can visit the site and see what the search positions for the next month on google will be using their google dance tool search.