 In statistics, "bias" is an objective property of an estimator.Bias can also be measured with respect to the median, rather than the mean (expected value), in which case one distinguishes "median"-unbiased from the usual "mean"-unbiasedness property.Bias is related to consistency in that consistent estimators are convergent and "asymptotically" unbiased (hence converge to the correct value as the number of data points grows arbitrarily large), though individual estimators in a consistent sequence may be biased (so long as the bias converges to zero); see bias versus consistency.