Latent Semantic Indexing - why it matters.

Last Update: October 14, 2013

I'm here with my happy head on, so you can relax.

You may have read my blog on Google Hummingbird recently, in which I pointed out how Hummingbird, Google's completely rewritten search algorithm, is a boon for writers and a horror story for people stuck with a traditional view of SEO. John followed this up with a different view which led to some debate in the comments section.

Hummingbird has reached the point where good content will rank you and keyword stuffing will kill you. What I didn't do enough of in my article was to deal with Latent Semantic Indexing (LSI), one of the key elements of the rewrite, although it appeared in a different form before.

LSI works by taking you key phrase or keyword and indexing your site firstly for that keyword, but secondly Google says it identifies "words in the same content which mean the same or similar". British author David Lodge refers to effective writing as containing "elegant variation". In other words, if you said something once then describe it in a different way the next time you mention it. I'll show you an example from a mythical website, firstly in the old style, secondly in the new style:

Old SEO

Keyword "dog training".

"Visit Thrashadog for all your dog training requirements. Here we take dog training seriously and provide dog training tailored for every dog's personal needs. If your dog needs dog training then give us a call, and we'll introduce him or her to the finest dog training in the South West."

Clearly I've exaggerated somewhat, but believe me when I say I've had similar sites to rewrite in the past. So how might this look if written for a) humans, and b) LSI.

Hummingbird SEO

Keyword "dog training"

"Visit Thrashadog for all your dog training requirements. Here we take our job seriously, and provide and teach all forms of canine correction, tailored to your pet's disposition. If you'd like to have your dog taught to walk to heel, sit at a kerb, avoid other dogs, or just be better behaved, then give us a call and we'll introduce you both to the finest training in the South West!"

Let's run by that again, with the LSI words highlighted:

"Visit Thrashadog for all your dog training requirements. Here we take our job seriously, and provide and teach all forms of canine correction, tailored to your pet's disposition. If you'd like to have your dog taught to walk to heel, sit at a kerb, avoid other dogs, or just be better behaved, then give us a call and we'll introduce you both to the finest training in the South West!"

You'll notice that I've highlighted "our Job" and"teach", as well as directly linked phrases that we know refer to dog training, like "have your dog taught" and "walk to heel". This is because Google fully understands context.

The word "job" in context will be linked by Google to "training", as will the word "teach". The longer highlighted words or phrases are all things you'd be looking for in a trained dog. Google is getting very twitchy about the overuse of keywords and will slaughter the site in the first example. The second example provides the sort of context Google loves. Note from our training that we only have our chosen keyword in the title and once in the text. Google wants to know what your site is about and then see you've backed it up with perfectly reasonable, focused content. Writing good content will improve your rankings. Period.

Just as a small extra, I revisited my website at about 06.45 this morning and removed two examples of my keyword from my home page. I've just checked and I'm the second organically ranked site on page one of Google out of 484,000,000 results. That's a jump of 6 places in five hours.

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Eddie C Premium Plus
Awesome post Paul. Great content is and will be the factor for ranking on Google, we've gone through this many time here at WA. We all must re-visit our pages/posts from our websites and remove keywords that are redundant and write it in a more reasonable focused content as if you were to explain it to a human being.
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georama Premium
Really amazing.
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famous Premium
The discussions of SEO go on and on. Here are some questions.

If one only uses the keyword once, how does Google know which keyword is most important, or does view all of the phrases equally?

In the course of normal speaking it's not uncommon for someone to repeat a keyword phrase. Are we allowed to repeat a keyword, or would we get penalized?

Should we try to use related keywords we select using Jaaxy, or would that just mess up our writing too badly?
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Paul Dean Premium
You're not using the key word once, you're using it once in the title(hopefully) once in the first paragraph, and MAYBE once somewhere else, although a lot of successful people don't. There are three essentials to keyword selection:

1. A large volume of traffic.
2. As little competition as possible.
3. A phrase that's highly relevant to your site's purpose.

If you can find a phrase that meets all those criteria then you should use it, because that will give you the greatest chance of somebody finding you. But if you make your text highly relevant too, then all the other associated phrased will lend weight to the site as a whole. Think of your keyword as a cold individual, alone on a bed. The other relevant words are the duvet he's wrapped up in.

I take your point about using the other Jaaxy phrases, but I'd say no, not deliberately. Write naturally, keep it on topic, and write lots. You may stumble upon some of those words, which is great if they don't sound forced, but ignore them otherwise.

To be clear, nothing I'm saying here contradicts or surpasses the training in the modules. I'm almost at the top of the first page of Google by following the training EXACTLY. If I have any edge it's that I've done a lot of research on Hummingbird and LSI and understand that if there are five ways to say one thing, you're better using all five than one of them five times.

If you can just write naturally, always keeping your subject in mind and not wandering off on a tangent (like I sometimes do), and you try not to repeat the same phrases over and over, then you should gallop up the ranks. Write like an expert, don't be afraid to use industry specific jargon PROVIDING you offer an explanation. People in your business may Google the words that no one else understands and you'll pick them up.
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GoldFish Premium
Thanks Paul. It is a very informative article. I have written my first article and was worried I couldn't incorporate my keywords again and again in it. Thanks for this blog.
If possible, Kindly visit my article at http://juicingandhealthyeating.com/juicing and provide your feedbackif this article meets the latest SEO. Thanks
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OldCodger Premium
"Thrashadog" - what have you unleashed, Paul? Through the laughter, I did manage to read the excellent content. Perhaps I'll get RSI from revising all my sites with LSI, but it makes a whole lot of sense to me, as it would encourage more thoughtful and creative writing. All for the better, methinks. Gugle understands? Who would have thunk it?
:) george
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OldCodger Premium
Our Gugle, in boundless Ether,
hallowed be thy Mainframe.
Thy rules do rule,
thy will be done,
on PC as it is on apple.
Give us this day our highest rank,
and optimise our keywords
as we strive for Latent Semantic Indexing
to advance over those above us.
For thou hast the power,
the hummingbird and the glory,
controlling our lives forever.
Ah, men!
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Paul Dean Premium
Do not mock the gods of t'internet, for your screen with surely freeze. Arthur: chapter 41, vs 9.
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