Latent Semantic Indexing
Latent Semantic Indexing [LSI] has no impact on SEO - and
When a whole bunch of patents were filed by Google in 2006, all
around information retrieval and associated capabiities, eyes were
on guard. Whenever Google does anything - SEO Chasers are in hot
pursuit, to figure out the impact on their website rankings.
To prove LSI is NOT having any effect on your Search Rankings.
Lets look at the evidence - that which we can measure.
Google does not own or use any patents on LSI - as far as can be
established. It uses its own proprietary algorithms for search and
LSI relies on the way different words, used in the same context,
to communicate the same meaning are used, and how often. For instance,
car and automobile can be used interchangeably in most instances,
as can cellphone and mobile phone. In the past, search engines could
not make this distinction and pulled results for each term independently.
Today, LSI provides a framwork upon which such word groups can be
associated and returned in search results to give broader output.
Over the 50 billion pages on the Net, compiling these relationship
matrices is quite a task.
So frequency will start to dominate. The words are decomposed into
around 300 rows using Singular Value Decomposition. This significantly
smaller subset of words represent all thousands of rows previously
Words are then scored based on 'similarity' in meaning to the words
in the 300 rows.
LSI works with words at the level of 'meaning', rather than the
group of letters that make up words. It also deals with different
tenses of the same word, and plurals of words. In spite of this,
Google results for plurals typically differ by over 20% from the
singular version, and search results on the first page are noticeably
distinct. Not something that indicates the use of LSI. Instead Google
has a better system, taking into account proximity of content across
billions of documents.
LSI is based on a rather loose academic theory. Google search uses
meaninful human related context - based on human behaviour and common
If you want a real sharp SEO Strategy beyond keyword density, anchor
text, backlinks etc, take a look at Referential Integrity [RI].
RI works with Google, rather than against it.
NEXT: Referential Integrity
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