  The Marshall and Sanow data set is the largest and most comprehensive data
set available quantifying handgun bullet effectiveness in humans. This article
presents an empirical model for relative incapacitation probability in humans
hit in the thoracic cavity by handgun bullets. The model is constructed by
employing the hypothesis that the wound channel and ballistic pressure wave
effects each have an associated independent probability of incapacitation.
Combining models for these two independent probabilities using the elementary
rules of probability and performing a least-squares fit to the Marshall and
Sanow data provides an empirical model with only two adjustable parameters for
modeling bullet effectiveness with a standard error of 5.6% and a correlation
coefficient R = 0.939. This supports the hypothesis that wound channel and
pressure wave effects are independent (within the experimental error), and it
also allows assignment of the relative contribution of each effect for a given
handgun load. This model also gives the expected limiting behavior in the cases
of very small and very large variables (wound channel and pressure wave), as
well as for incapacitation by rifle and shotgun projectiles.
