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Interpreting Accuracy

By definition, an EBV is an estimate of an animal’s true breeding value. The “accuracy” figure produced with each EBV provides a measure of the stability of the EBV and gives an indication of the amount of information that has been used in the calculation of that EBV. The higher the accuracy the lower the likelihood of change in the animal’s EBV as more information is analysed for that animal, its progeny or its relatives.

Accuracy figures are reported as a percentage (%) between 0 – 99.

In most cases where an EBV is presented, the accuracy of the EBV will be reported in either the column immediately following the EBV or the row beneath the EBV.

The following guide may be useful for interpreting accuracy:

Less than 50% accuracy - the EBVs are preliminary. EBVs in this range will have been calculated based on very little information. These EBVs could change substantially as more direct performance information becomes available on the animal.

50-74% accuracy - the EBVs are of medium accuracy. EBVs in this range will usually have been calculated based on the animal’s own performance and some limited pedigree information.

75-90% accuracy - the EBVs are of medium-high accuracy. EBVs in this range will usually have been calculated based on the animal’s own performance coupled with the performance for a small number of the animal’s progeny.

More than 90% accuracy - the EBVs are a high accuracy estimate of the animal’s true breeding value. It is unlikely that EBVs will change considerably with addition of more progeny data.

Although the accuracy of an EBV should be considered, animals should be compared on EBVs regardless of accuracy. Where two animals have the same EBV however, the animal with the higher accuracy would normally be used more heavily than the bull with the lower accuracy because the results can be predicted with more confidence.

Remember, all information that is known about an animal and its relatives is considered in the calculation of its EBVs. Subsequently, the EBV will be the best estimate available of an animal’s genetic merit, regardless of accuracy.