Why does increasing the number of animals improve the accuracy of the mean in a contemporary group?

Why does increasing the number of animals improve the accuracy of the mean in a contemporary group?

• A. It guarantees higher genetic variance.
• B. More in the group means a better measure of the mean which accounts for environment.
• C. It reduces the effect of measurement error to zero.
• D. It ensures perfect environmental control.

Answer: (B)

Increasing the number of animals in a contemporary group improves the precision of the mean because it averages out random, non-genetic influences. Each animal carries its own environmental effects, handling differences, and measurement error. When you include more animals, these random factors tend to cancel each other out, so the group mean becomes a more reliable estimate of the true average performance for that group. This happens because the standard error of the mean shrinks as more observations are added (it decreases roughly with 1/sqrt(n)). It’s important to note that this doesn’t change the underlying genetic variance, nor does it make measurement error disappear or environmental control perfect. It simply reduces the impact of random variation on the calculated mean, making it a truer reflection of the group’s average performance.

Increasing the number of animals in a contemporary group improves the precision of the mean because it averages out random, non-genetic influences. Each animal carries its own environmental effects, handling differences, and measurement error. When you include more animals, these random factors tend to cancel each other out, so the group mean becomes a more reliable estimate of the true average performance for that group. This happens because the standard error of the mean shrinks as more observations are added (it decreases roughly with 1/sqrt(n)).

It’s important to note that this doesn’t change the underlying genetic variance, nor does it make measurement error disappear or environmental control perfect. It simply reduces the impact of random variation on the calculated mean, making it a truer reflection of the group’s average performance.