What is the effect of measurement bias on the estimated contemporary group mean?

What is the effect of measurement bias on the estimated contemporary group mean?

• A. It has no effect on the mean.
• B. It biases the mean.
• C. It always increases accuracy.
• D. It reduces environmental variance.

Answer: (B)

Measurement bias introduces a systematic error into observations, meaning the measured phenotype is consistently off from the true value. When you average measurements within a contemporary group to estimate its mean, that constant error adds to every observation, so the computed mean is shifted by the bias amount. In other words, the estimated contemporary group mean is biased away from the true mean. The direction depends on the bias sign: a positive bias raises the mean, a negative bias lowers it. This undermines accuracy of the mean estimate, not its precision, and it can also distort comparisons between groups. Correcting for bias is essential to obtain an unbiased, meaningful estimate of the group mean.

Measurement bias introduces a systematic error into observations, meaning the measured phenotype is consistently off from the true value. When you average measurements within a contemporary group to estimate its mean, that constant error adds to every observation, so the computed mean is shifted by the bias amount. In other words, the estimated contemporary group mean is biased away from the true mean. The direction depends on the bias sign: a positive bias raises the mean, a negative bias lowers it. This undermines accuracy of the mean estimate, not its precision, and it can also distort comparisons between groups. Correcting for bias is essential to obtain an unbiased, meaningful estimate of the group mean.