Table 1. Relationships between $K_X\mathbf{}\mathrm{(}\xi \mathrm{)}$ and quantities in cellular lineage statistics.

	Quantities in lineage statistics	Symbol	Correspondence to $K_X(\xi )$
Fitness	Population growth	$\tau \mathrm{\Lambda }$	$K_X(1)$
	Chronological mean fitness	${⟨h(X)⟩}_{\mathrm{cl}}$	$K_X^{\prime }(0)$
	Retrospective mean fitness	${⟨h(X)⟩}_{\mathrm{rs}}$	$K_X^{\prime }(1)$
	Chronological fitness variance	$\mathrm{Var}{[h(X)]}_{\mathrm{cl}}$	$K_X^{\prime \prime }(0)$
	Retrospective fitness variance	$\mathrm{Var}{[h(X)]}_{\mathrm{rs}}$	$K_X^{\prime \prime }(1)$
Selection strength	Jeffreys divergence bet. $Q_{\mathrm{cl}}(X)$  and $Q_{\mathrm{rs}}(X)$	$S_{\mathrm{JF}}[X]$	$K_X^{\prime }(1)-K_X^{\prime }(0)$
	KL divergence of ${\displaystyle Q_{\mathrm{c}\mathrm{l}}(X)}$ from  ${\displaystyle Q_{\mathrm{r}\mathrm{s}}(X)}$	$S_{\mathrm{KL}}^{(1)}[X]$	$K_X(1)-K_X^{\prime }(0)$
	KL divergence of ${\displaystyle Q_{\mathrm{r}\mathrm{s}}(X)}$ from  ${\displaystyle Q_{\mathrm{c}\mathrm{l}}(X)}$	$S_{\mathrm{KL}}^{(2)}[X]$	$K_X^{\prime }(1)-K_X(1)$
Growth rate gain/loss	Growth rate gain	${\displaystyle S_{\mathrm{K}\mathrm{L}}^{(1)}[D]/\tau \mathrm{\Lambda }}$	$1-K_D^{\prime }(0)/K_D(1)$
	Additional growth rate loss upon perturbation	$-S_{\mathrm{KL}}^{(2)}[D]/\tau \mathrm{\Lambda }$	$1-K_D^{\prime }(1)/K_D(1)$