TABLE II. Definitions of the main metrics.

The superscript “0” and “1” denote quantities that are based on the total population (including new infections) and a cohort (excluding new infections), respectively. Quantities with subscript “c” and “u” denote confirmed and untested pools (for example, $N_{\text{u}}^0(t)$ is the total number of untested individuals at time t) that must be inferred using other measurements such as random testing. We have suppressed the time dependences for notational simplicity.

Subpopulation╲Metric	Fatality Ratios	Resolved Mortality w/inf	Resolved Mortality w/o inf	Individual Risk
confirmed (tested)	$\text{CFR}=\frac{D_{\text{c}}^0}{N_{\text{c}}^0}$	$M_{\text{p}}^0=\frac{D_{\text{c}}^0}{D_{\text{c}}^0+R_{\text{c}}^0}$	$M_{\text{p}}^1=\frac{D_{\text{c}}^1}{D_{\text{c}}^1+R_{\text{c}}^1}$	${\overline{M}}_1=\frac{{\overline{P}}_{\text{d}}}{{\overline{P}}_{\text{d}}+{\overline{P}}_{\text{r}}}$
total (tested+untested)	$\text{IFR}=\frac{D_{\text{c}}^0+D_{\text{u}}^0}{N_{\text{c}}^0+N_{\text{u}}^0}$	${\mathcal{M}}_{\text{p}}^0=\frac{D_{\text{c}}^0+D_{\text{u}}^0}{D_{\text{c}}^0+D_{\text{u}}^0+R_{\text{c}}^0+R_{\text{u}}^0}$	${\mathcal{M}}_{\text{p}}^1=\frac{D_{\text{c}}^1+D_{\text{u}}^1}{D_{\text{c}}^1+D_{\text{u}}^1+R_{\text{c}}^1+R_{\text{u}}^1}$	not defined