Phenotypic selection gradient
= Phenotypic selection gradient
{title2=$\boldsymbol\beta$}
A <vector> describing direct selection on measured <phenotypic traits>, conditional on the other measured traits. In a local deterministic fitness model it can be written $\boldsymbol\beta=\nabla_{\mathbf z}\log w$; population regression estimates require their own sampling and fitness assumptions. This differs in context from a rare-mutant invasion <selection gradient>.