Author: Bert Klei, Ph.D.
University of PIttsburgh Medical Center
This article specifically applies to Bernese Mountain Dogs | The Berner-Garde Database COI calculator; however, the article does provide discussion and general information on use of COI, and COI calculators.
"An inbreeding calculator determines the COI. In genetic terms this is the probability that the two alleles at a locus are identical by descent. In practice people think about this as the chance that the two copies of a gene come from a single copy of a gene from a single ancestor. When breeders talk about "doubling up" on traits, this is to what they are referring."