The trunsored model, which is a new incomplete data model regarded
as a unified model of the censored and truncated models in lifetime
analysis, can not only estimate the ratio of the fragile population
to the mixed fragile and durable populations or the cured and fatal
mixed populations, but also test a hypothesis that the ratio equals
to a prescribed value with ease.
Since SARS showed a severe death rate, our concern is to know such
a death rate as soon as possible after a similar outbreak begins.
The epidemic analysis of SARS differs from the lifetime analysis,
but the probabilistic growth curves fitted to the infected cases,
fatal cases, and cured cases of SARS can similarly be treated as
the lifetime analysis. Using the truncated data models to the infected
and fatal cases with some censoring time, we may estimate the total
(or final) numbers of the patients and deaths, and the death rate
may be estimated by these two numbers. We may also estimate the
death rate using the numbers of the patients and recoveries, but
this estimate differs from that using the numbers of the patients
and deaths, especially when the censoring time is located at early
To circumvent this inconsistency, and to obtain much more reliable
estimates, we propose a mixed trunsored model, an extension of the
trunsored model, which can use the data of the patients, deaths,
and recoveries simultaneously. The estimate of the death rate and
its error are easily and stably obtained in a numerical sense. This
paper mainly treats the case in Hong Kong.