Date of this Version
Biases in evaluation of sires result from misidentified records in the sire group averages used for sire evaluation. The bias increases as the fraction of misidentified cows increases. Use of variance components estimated from misidentified records also contributes to the bias. Estimates of the correlation between estimated and true genetic value, as well as estimates of genetic progress due to selection, are biased when misidentified records are included in sire group averages.