Credibility factor
= Credibility factor
{title2=$Z=na/(na+v)$}
The credibility factor in the <Bühlmann model> is the weight $Z=na/(na+v)$ placed on the <sample mean> after $n$ observations. The remaining weight is placed on the population <expected value>. More experience or larger <variance of hypothetical means> increases $Z$; larger <expected process variance> decreases it.