Entendendo o ebv, indices de seleção e acurácia

ABERDEEN-ANGUS BREEDPLAN
Understanding the EBVs, Selection Indexes and Accuracy
EBVs
An animal's breeding value is its genetic merit, half of which will be passed on to its progeny. While we will never know the exact breeding value, for performance traits it is possible to make good estimates. These estimates are called Estimated Breeding Values (EBVs).
In the calculation of EBVs, the performance of individual animals within a contemporary group is directly compared to the average of other animals in that group. A contemporary group consists of animals of the same sex and age class within a herd, run under the same management conditions and treated equally. Indirect comparisons are made between animals reared in different contemporary groups, through the use of pedigree links between the groups.
EBVs are expressed in the units of measurement for each particular trait. They are shown as positive or negative differences between an individual animal's genetics difference and the genetic base to which the animal is compared. For example, a bull with an EBV of +30 kg for 400-Day Weight is estimated to have genetic merit 30 kg above the breed base of 0 kg. Since the breed base is set to an historical benchmark, the average EBVs of animals in each year drop has changed over time as a result of genetic progress within the breed.
The absolute value of any EBV is not critical, but rather the differences in EBVs between animals. Particular animals should be viewed as being "above or below breed average" for a particular trait. The breed average for the current two year old animals are reported with the selected animals’ EBVs.
Whilst EBVs provide the best basis for the comparison of the genetic merit of animals reared in different environments and management conditions, they can only be used to compare animals analysed within the same analysis. Consequently, Aberdeen-Angus BREEDPLAN EBVs cannot be validly compared with EBVs for any other breed.
EBVs are published for a