It’s a name for an important special case of “different denominators lead to different averages”, where the cause of the perhaps-unexpected denominator is that some quantities you’re interested in estimating correlate with how likely you are to observe them.
That correlation is a key point here, and any description of the effect that doesn’t include it is describing at most part of it.
It’s a name for an important special case of “different denominators lead to different averages”, where the cause of the perhaps-unexpected denominator is that some quantities you’re interested in estimating correlate with how likely you are to observe them.
That correlation is a key point here, and any description of the effect that doesn’t include it is describing at most part of it.