  Many disease models focus on characterizing the underlying transmission
mechanism but make simple, possibly naive assumptions about how infections are
reported. In this note, we use a simple deterministic
Susceptible-Infected-Removed (SIR) model to compare two common assumptions
about disease incidence reports: individuals can report their infection as soon
as they become infected or as soon as they recover. We show that incorrect
assumptions about the underlying observation processes can bias estimates of
the basic reproduction number and lead to overly narrow confidence intervals.
