Ch. Mallinckrodt et al., THE EFFECT OF SELECTIVE REPORTING ON ESTIMATES OF WEANING WEIGHT PARAMETERS IN BEEF-CATTLE, Journal of animal science, 73(5), 1995, pp. 1264-1270
The effect of selective reporting on estimates of weaning weight param
eters in beef cattle was evaluated by comparing REML estimates from un
altered and altered simulated data. Selective reporting reduced estima
tes of weaning weight direct (WWD), maternal milk (MAT), and error var
iances. However, heritability estimates were not greatly affected beca
use the reductions in variance estimates were relatively proportionate
. When the true value for the direct-maternal (DM) correlation was zer
o or negative, selective reporting caused estimates of DM to be less p
ositive or more negative in 50 of 62 comparisons, with an average chan
ge of -.136. When the true value for DM was positive, selective report
ing increased the positive magnitude of DM estimates in 12 of 20 compa
risons, with an average change of +.040. In BLUP of unaltered data wit
h a true DM value of -.09, using a -.28 and a zero DM correlation redu
ced the correlation of MAT EPD with true values .065 and .041, respect
ively. These results suggest that the reliability of parameter estimat
es (and BLUPs) would be improved by estimating parameters from represe
ntative subsets of data free of reporting bias.