On the face of it the CI measure seems to me as being a numerical way of identifying how 'open' a race is in terms of the odds on offer.

For example a 12 horse race with the lowest priced fave at $5.00 vs a 12 horse race with a lowest priced fave at $2.50, if all other horses odds are the same you'd say the first race is more 'open' and hence would have a lower CI value.

I obviously haven't looked into this CI calculation or its use much at all, but on the face of it as i've said it seems like simply an indicator as to how open a field is. The benefit of this is that by having it as a numerical value you can base systems or selections around it like, only bet if the CI is below 0.15 as this represents an open race where I can achieve value on my selections.

By looking at a race yourself you should be able to determine this anyway, but by having it numerically represented in your face it could act as a more effect mental trigger possibly?

Anyway thats just my take on it based on the last 10-15 posts in this thread. Interested in further discussion though.