This factor has been calculated for a large number of Golden Retrievers. This information can
be found on K9data
This study deals with a subset of that data.
The last update was September 2008.
The following plot of COI versus lifespan shows a lot of scatter (RSquared->0.0122272).
The following histogram illustrates the data distribution in COI's.
The following chart shows that MACHs have the lowest COIs on average while SDHF Goldens have the largest.