Measurement error and observed heritability ($h_{\mathrm{obs}}^2=q{h}_{\mathrm{true}}^2$)

If observed variation is true-score variation $V_T$ plus independent measurement error $V_{ϵ}$, and genetic variance $V_G$ is part of $V_T$, then $h_{\mathrm{obs}}^2=V_G/(V_T+V_{ϵ})$. Writing measurement reliability as $q=V_T/(V_T+V_{ϵ})$ gives the displayed identity. Removing independent error can raise the heritability estimate without changing the genetic contribution to the true score. The result requires this measurement model; it does not identify measurement reliability by dividing arbitrary estimates from different longitudinal models.