Google and Latent Semantic Indexing
Sep/13/09 07:06
The foundation of what it takes to achieve positive relevancy scores in the eyes of Google is constantly shifting. Recently, the shift many sites are experencing may be a result of Google's apparent focus on Latent Semantic Indexing (LSI). LSI allows a search engine to determine what a page is about outside of specifically matching search query text.
The foundation of what it takes to achieve positive relevancy scores in the eyes of Google is constantly shifting. Recently, the shift many sites are experiencing may be a result of Google's apparent focus on Latent Semantic Indexing (LSI). LSI allows a search engine to determine what a page is about outside of specifically matching search query text.
"Latent semantic indexing adds an important step to the document indexing process. In addition to recording which keywords a document contains, the method examines the document collection as a whole, to see which other documents contain some of those same words. LSI considers documents that have many words in common to be semantically close, and ones with few words in common to be semantically distant. This simple method correlates surprisingly well with how a human being, looking at content, might classify a document collection. Although the LSI algorithm doesn't understand anything about what the words mean, the patterns it notices can make it seem astonishingly intelligent." source
Latent semantic indexing can also be used to look at the link profile for the individual pages on your website. If all your links are heavy for a few particular words or phrases and light on other similar phrases then your site may not rank as well.
How do I Know What Words are Related?
As Aaron Wall suggests, there are a variety of options to know what words are related to one another.
* Search Google for search results with related terms using a ~. For example, Google Search: ~seo will return pages with terms matching or related to seo and will highlight some of the related words in the search results.
* Use a lexical database
* Look at variations of keywords suggested by various keyword suggestion tools.
* Write a page and use the Google AdSense sandbox to see what type of ads they would try to deliver to that page.
* Read the page copy and analyze the backlinks of high ranking pages.
For me, it all comes back to context within the content. If you simply focus on specific keywords and never back them up with relevant content or other related keywords, LSI is going to lower the value of those pages.
"Latent semantic indexing adds an important step to the document indexing process. In addition to recording which keywords a document contains, the method examines the document collection as a whole, to see which other documents contain some of those same words. LSI considers documents that have many words in common to be semantically close, and ones with few words in common to be semantically distant. This simple method correlates surprisingly well with how a human being, looking at content, might classify a document collection. Although the LSI algorithm doesn't understand anything about what the words mean, the patterns it notices can make it seem astonishingly intelligent." source
Latent semantic indexing can also be used to look at the link profile for the individual pages on your website. If all your links are heavy for a few particular words or phrases and light on other similar phrases then your site may not rank as well.
How do I Know What Words are Related?
As Aaron Wall suggests, there are a variety of options to know what words are related to one another.
* Search Google for search results with related terms using a ~. For example, Google Search: ~seo will return pages with terms matching or related to seo and will highlight some of the related words in the search results.
* Use a lexical database
* Look at variations of keywords suggested by various keyword suggestion tools.
* Write a page and use the Google AdSense sandbox to see what type of ads they would try to deliver to that page.
* Read the page copy and analyze the backlinks of high ranking pages.
For me, it all comes back to context within the content. If you simply focus on specific keywords and never back them up with relevant content or other related keywords, LSI is going to lower the value of those pages.