From: hes@unity.ncsu.edu (Henry E. Schaffer)
Newsgroups: rec.guns
Subject: Re: Handgun Ammunition Debate
Date: 4 Oct 92 02:27:18 GMT
Organization: North Carolina State University

In article <1992Oct2.235147.1042@nsc.nsc.com> nsc!jrr@decwrl.dec.com (Jerry Roe) writes:
#In article <1992Sep27.162324.18931@ncsu.edu> hes@unity.ncsu.edu (Henry E. Schaffer) writes:
##In article <1992Sep26.194530.10787@henson.cc.wwu.edu> n9020351@henson.cc.wwu.edu (James Douglas Del-Vecchio) writes:
###nsc!jrr@decwrl.dec.com (Jerry Roe) writes:
###
####*in those cases where there's only one torso hit*, what percentage
####of them are stoppers?  In other words, if there's only one torso hit,
###No, what Marshall's stats measure can more accurately be summarized
###as: 
###*In those cases where only one torso hit is required*, how does everthing
###turn out?
### ...
## ...
#But this isn't what Marshall is doing.  Your example presumes a round
#that can *only stop* with one shot if it hits the central nervous system.

  I don't know what Marshall is doing since I haven't read his book.
I only know what other posters have said that Marshall is doing - and
they say that he is discarding/selecting data.

#Marshall is saying, of all the rounds out there, when the shooter does
#his job (puts the round in center torso), which one does the best job?
#Once it is placed in the proper spot?  

  Regardless of what he says - we must be concerned about what his
method of data analysis *does*.  If my understanding of his method is
right, then his analysis is *not* asking this question.  My examples
were to show that applying his method to (somewhat) realistic data
could give very misleading answers which did *not* answer the 
question you say he asks.

#He's not saying shoot-shoot-shoot
#and see what happens.  He's saying, shoot once in the center torso and
#the guy either stops or not, and in the case of the .357 125-gr HP,
#97% of the time the answer is yes, the guy stops hostilities.

  But this is *not* what he is doing.  He takes data in which there
is a mixture of "shoot once", "shoot twice", ..., "shoot n times"
and discarding all but the first category.  Unless we *know* that
this discarding doesn't introduce any bias, then we can't take his
analysis as answering this question.  (Please note that I like the
.357 Magnum - but that with an unknown bias possible it could be
that the real effectiveness of the .357 vs. other calibers is
either higher or lower than this 97%.)  The criteria that real
shooters use to decide when to stop shooting certainly is variable,
and certainly is "personal" (i.e. Marshall doesn't have any control
over this.)  So Marshall comes in later, takes the data, and then is
trying to make sense of it.  He is not establishing the stopping rule.
#
#If you presume a case where *no* round could stop with one shot unless
#it hit the central nervous system, then that's a fair comparison.  But
#that's not the case, clearly.  Marshall applies the same criteria to
                                                     ^^^^^^^^^^^^^
  But if the criteria lead to bias (as in my extreme examples) then
this is hardly a consolation.

#every round he studies, and the one round that keeps coming up on top
#is the .357 125-gr JHP.

  This doesn't say that his method is good. 

--henry schaffer  n c state univ