Area compatibility factor

In survival analysis, the area compatibility factor, "F", is used in indirect standardisation of population mortality rates.

:$F\; =\; frac\{sum\_x\; \{\}^sE\_\{x,t\}^c\; \{\}^sm\_\{x,t\{sum\_x\; \{\}^sE\_\{x,t\}^c\}\; left/frac\{sum\_xE\_\{x,t\}^c\; \{\}^sm\_\{x,t\{sum\_x\; E\_\{x,t\}^c\}\; ight.$

where:

:$\{\}^sE\_\{x,t\}^c$ is the standardised central exposed to risk from age "x" to "x" + "t" for the standard population,

:$E\_\{x,t\}^c$ is the central exposed to risk from age "x" to "x" + "t" for the population under study and

:$\{\}^sm\_\{x,t\}$ is the mortality rate in the standard population for ages "x" to "x" + "t".

"F" is then multiplied by the crude mortality rate to arrive at the indirectly standardised mortality rate.