This section covers the Long Tail Index column, one of the long tail columns, located on the Zoom Analysis Screen:

This column is colored coded blue, as are all the long tail columns, and is populated only when the keyword is a Long Tail Keyword.  The picture below shows the column header of the Long Tail Index.

The Long Tail Keyword columns have a background color of light blue so that their meaning is easily identified.

The Long Tail Index (LTI) came into existence due to the frustration of being faced with hundreds of long tails all having zero CPC and zero CPD.  There needed to be a way to distinguish which long tails were more valuable than others without having to wade through them all by hand, one-by-one.

This is accomplished by pulling apart the components that make up a long tail and examining their individual value.  Then we contrast those findings with the intrinsic value of the keyword itself.

The LTI column and the Market Convergence column are similar up to this point.

The goal was to distinguish "valid" long tails such as "evening primrose oil acne" from such general terms as "buy evening primrose oil". 

Therefore you will find some Long Tails that have a high CPC Tail and a high CPD Tail, have a low LTI because the term in the tail is too general.

Such terms will score highly in the Market Convergence column, but low here in the LTI column.

High scoring LTI will be reserved for words whose tail is more likely to be considered "expert verbiage" for this particular theme.