BOLT
with substantial index movement, these animals will be the exception to the rule.
9. How does BOLT improve our calculation of accuracy?
“ True” accuracy can be thought of as the gold standard of accuracy. It is statistically unbiased, and therefore the ultimate measure of accuracy. True accuracy is the accuracy resulting from direct calculation. Unfortunately, even with the massively powerful computing capacity now in existence, the direct calculation of accuracy is not possible on datasets the size of ours. Because we cannot calculate accuracy directly, other approaches to accuracy calculation have been developed.
In our Cornell evaluation platform, and all others in existence other than BOLT, the calculation of the accuracy associated with each EPD is achieved through“ approximation” methods. It has long been known these methods are a very crude approach to the calculation of accuracy— tending to overestimate accuracy.
Another approach to the calculation of accuracy is via“ sampling” methodology. Sampling is shown to be a more accurate predictor of accuracy. In fact, the results of this method were reported to be virtually identical to
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true accuracy. Unfortunately, due to its computationally intense nature, sampling has long been thought an infeasible approach to the calculation of accuracy on large databases.
BOLT, however, has changed the landscape in this area. By employing unique computing strategies that leverage both software and hardware efficiencies, BOLT performs what was previously unthinkable— utilizing a sampling methodology to calculate what is essentially true accuracy.
Because BOLT can calculate true accuracy, we can put more confidence in our accuracy metrics. Put another way, unlike with approximation, we can count on the predicted movements associated with possible change holding true over time. This was not the case with our Cornell system nor any other system in existence.
10. Why do the carcass EPDs generally have an increase in accuracy with BOLT while this is not a case for other traits?
You will notice that while the Multi-breed Genetic Evaluation powered by BOLT will generally produce lower accuracies than the Cornell system for growth and calving ease traits, the opposite is true for carcass traits.
One reason behind the differing accuracy outcomes is several years ago the evaluation team developed a way to temper inflated accuracies in the Cornell carcass evaluation. Unfortunately, this was not possible for growth traits.
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Another reason is that the Cornell system only used the carcass and its corresponding ultrasound trait( e. g., marbling score and IMF) to predict carcass EPDs, while records on several additional correlated traits are leveraged with the BOLT system.
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