Removed compartment
= Removed compartment
{title2=$r=R/N$}
The <removed compartment> consists of people permanently excluded from both acquiring and passing on <infection> in the <SIR model>. Its count is $R(t)$ and its <fraction> is $r(t)=R(t)/N$. Removal can represent regained health with lasting <immunity>, or another permanent exclusion from acquiring or passing on <infection>; it need not mean being healthy again. Here there are no deaths. In a variant that counts deaths within $R$, <conservation of population> would concern the original cohort, rather than the number currently alive.https://www.damtp.cam.ac.uk/user/tong/mathbio/mathbio1.pdf[David Tong, Mathematical Biology, section 1.5.1]{ref}