Abstract: | Summary Procedures to estimate a dose of which the incidence probability is very small (e.g. 10−6) have been developed to evaluate the safety of chemical compounds. To compare models for estimation of safe doses quantitatively,
a measure of the heaviness of tail of a distribution and a measure of tail at the origin are introduced. These measures have
a theoretical basis for the comparison of tail behavior between distributions. Using the two measures, a tail ordering is
defined to present a criterion for the comparison of models and is discussed for the probit, the logit, the Weibull, the (generalized)
multihit, the (generalized) multitarget and the multistage models.
The multistage model is most conservative among them, while the probit model has the reverse property. The Weibull model is
more conservative than the logit. The multihit and multitarget models are found to be more sensitive than the Weibull and
the logit.
The Institute of Statistical Mathematics National Institute of Environmental Health Sciences |