Conditionally unbiased estimator
= Conditionally unbiased estimator
{title2=$E_\theta(\widehat\theta\mid\mathcal C)=\theta$}
An estimator is conditionally unbiased for a parameter if its <expectation>, conditional on the specified observation or selection event, equals that parameter. Unconditional unbiasedness does not imply this property after selection. Independent new-stage data and the <Rao-Blackwell theorem> can provide useful constructions.