Understanding LSI To Help You Rank Better

April 9, 2009 · Filed Under google, On Page SEO, SEO Advice, SEO Tips 

I thought I’d take a moment to explain to you what LSI is and why it’s important to your overall SEO efforts.

A lot of people it seems are very confused about how LSI fits into their overall SEO plan or even what it is.

LSI stands for Latent Semantic Indexing and while a very large and complicated phrase, it really means nothing more than using “related words and phrases” throughout your content.

Let’s take an example.

Let’s say that you were writing a web page on the topic of “iPhones”.  As you’re writing this content, you might naturally use related words and phrases such as “Mac”, “Apple”, “computer”, “cell phone”, etc.

That’s where LSI comes into play.  All of those related words, those semantically related words relate to the overall topic of that web page.  It is not the same thing as the plural of a word, LSI means the “semantically” related word or phrase plurals are simply “more than one”.

And Google knows this.

There’s a wonderful report that you should take time to read called “Patterns in Unstructured Data” provided by the National Institute for Technology in Liberal Education or NITLE which gives a fantastic explanation of how LSI works .

If you do a search on “Tiger Woods” or “Apple”, Google is smart enough to detect a few things about these terms such as the fact that Tiger Woods is a golfer, and that Apple is a company that has iPhones.

This would mean that if you created a web page about iPhones another likely word you might include on your page would be “Apple”.

Here’s a screen shot from Google when searching on the term “Apple”.  Notice in all of the initial 10 listings are occurrences of the computer company not the actual fruit.  And at the bottom of the page are still even more related words to “Apple”.

The same holds true for any words and phrases.  And Google makes it easy for us to spot what it believes are related words to virtually any term you decide to create a web page on.

While at Google.com place the tilde symbol ~ directly in front of each word you intend on using within your content.  Google will return to you what it believes to be semantically related words for each term you placed after that symbol.

Let’s take the example of the word “soap”.  Soap is a pretty generic term, it could mean the soap you wash with, a “Soap Opera” or even the protocol “SOAP” which stands for Simple Object Access Protocol.  How Google determines the relevance of the word you’re writing about is by also taking a look at the semantically related words you use within that content.

So if you were writing about the kind of soap you wash with, you might use terms like:

  • spa
  • body
  • candle
  • scented
  • bar
  • massage

On the other hand if you were writing about a soap opera you might use terms like:

  • Guiding Light
  • The Young and the Restless
  • The Bold and the Beautiful

The fact is, Google knows that if it finds the word “soap” in the same document as “body”, “candle” or “spa” you are most likely referring to bath soap and it will rank you accordingly.

This is why semantically related terms or LSI is so important.  It is using words and phrases throughout your content that all relate to the overall word or phrase of the content itself.

This is also why plurals are not helpful.  Plurals are not semantically related terms.  They are simply, plurals.  As an example, if you used the words “soap” and “soaps” on a web page, Google would have no idea what to do with that content because there are no additional semantically related terms on the page.

The bottom line is, when writing your content you do want to use semantically related terms within that content so that the search engines understand what that web page is about. This will help the search engines understand and rank your web pages accordingly.

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Comments

3 Responses to “Understanding LSI To Help You Rank Better”

  1. mark smith on April 14th, 2009 4:15 pm

    Did you see the most recent videos by Leslie Rhode at Stompernet? He debunks the whole idea of LSI and just wondered if you had seen that.

    Let me know what you think of his referential integretity theory.

    Mark

  2. Kristine on April 14th, 2009 4:55 pm

    I actually have seen the video by Leslie which prompted me to write this post in a “PC” manner. Mainly because of the old adage “any publicity is good publicity”.

    That said, I have to be careful what I say here for reasons I need to keep to myself.

    But suffice it to say that LSI does work; it’s not some “super-secret” method, it’s just simple, basic common sense and I’m afraid for those who don’t take it into account on their sites.

    There’s actually no way to make a web page, blog post or other piece of content readable without using LSI; most people use it every day and aren’t even aware that they’re doing so.

    The way I see it, is that if people decide to not use related words and phrases on their sites then I guess that’s just less competition for others to worry about.

    I have not watched the “referential integrity theory” video either for a couple of reasons. The main one being I simply don’t have the time. The other reason is again, for reasons I’ll keep to myself.

    That said, this is my personal opinion. Take it for what you will. I do suggest however that those considering not using LSI do a little split-test of their own and see what happens.

    Thanks for the comment Mark.

  3. Phil Henderson on May 12th, 2009 6:00 am

    I believe there is substance in LSI on your websites or blogs; after all it is the how people “naturallly” decide if a site is relevant to their search term or to just click off onto something else.

    My tests are proof that LSI is in use and that we shouldn’t ignore the importance of its usage. Another way to test this is with the use of your adwords campaign and the “relevancy score” when people click through from your advert to your landing page or site. The more relevant the content the more the visitor and Google will love you and the cheaper your clicks will become.

    Like everything else its up to the individual to run their own tests and see how their sites are indexed by Google.

    Have fun and never stand still ;-)