Keith Rogan
New member
OK, I read the article and its based on the supposition that Marshall is pushing his data base as a statistical predictor - a claim he has never made.
Each time new data is released, there are deletions (and additions one supposes) to old data. Maybe a shooting credited in 91 is found to not fit the criteria - the dude was shot already by another cop, etc.
The following is from Dale Towerts "Stopping Power Page":
Misconceptions and Limitations
by Kyrie Ellis 4 May 1996
There has always been much debate, frequently acrimonious, concerning the ability of any specific pistol cartridge to "stop" an attacker. People have tended to develop a fondness for a particular cartridge, and denigrate all others as being inferior in terms of "stopping power".
At times this debate has almost assumed the character of a religious war, complete with slogans ("They all fall to ball!").
Which is why I like Marshall's information.
For the first time we have information about how pistol cartridges actually work in real life. No "simulated tissue", human cadavers, animals, or war stories. Just information about what has actually happened when people were forced to shoot other people.
Which has left us with another, different, set of problems. How can we use Marshall's information? How do we avoid misusing his information? Which is why I've written this up, and submitted it to the "Stopping Power" page. My intent is to identify the misconceptions people (mostly gun magazine authors) seem to have formed about Marshall's information, and the limitations on the usefulness of that information. The format I've chosen (mostly because I couldn't think of a better one) is a statement commonly made about Marshall's information which is either mistaken or misleading, followed by an explanation of why that statement is mistaken or misleading.
"Marshall's study is scientific."
This statement is mistaken. In order for a study to be scientific, it must follow the scientific method. Which means formally stating a hypothesis, constructing an experiment to disprove that hypothesis, conducting that experiment, and presenting the results for review and replication by other researchers. Marshall did none of these things. He just collected information and published it. In the strict sense of the word, there is nothing "scientific" about Marshall's work. Nor could there be. Conducting an experiment where human test subjects are shot (frequently to death) is not something which can (or should!) be done. Nor would such an experiment have any real world value. Conditions in a laboratory can never duplicate conditions in the field.
"Marshall's study is not scientific."
This statement, while true, is misleading. The problem is that it assumes information must be obtained via experiment to be valid or useful. We don't need to conduct an experiment to determine that fire is hot, or that being shot is bad for our health. Nor is information gained from a scientific experiment necessarily valid or useful. Consider that scientific research once was used to prove that ionising radiation was beneficial to our health and well being...
"Marshall's statistics..."
Any statement which refers to Marshall's information as "statistics" or "statistical" is mistaken. [Er, I must confess to occasionally being guilty here. - Dale] What people refer to as Marshall's "statistics" is really the proportion of people who stopped being aggressive after being shot once in the torso, expressed as a percentage. Unlike ball scores and batting averages, each case in Marshall's study had only two outcomes - a "stopped" or a "not stopped". Events which have only two outcomes are not suitable subjects for statistical study, since they cannot have any of the customary statistical measurements of central tendency (such as mean, median, or mode), or of variation (such as variance or standard deviation). The problem here is that we are so accustomed to seeing statistical data presented as percentages that we automatically assume all percentages are statistical.
"Marshall's sample..."
Any statement which refers to the shootings in Marshall's data base as a "sample" is misleading at best, and mistaken at worst. The word "sample" is generally used to describe a subset of events, taken from a larger set of events, because the whole set of events is too large to be manageable. Samples intentionally exclude qualifying events. Marshall pursued all of the shootings he could. He did not pick and choose from qualifying shootings. His data contains all of the events which met the criteria of one shot to the torso, and to which he had access. The reason that this is an important distinction is that the inclusion of all available information removes any objections to Marshall's information based on claims of "sampling error" - there is no sample. Which is not to say that Marshall's information truly represents the effectiveness of all cartridges. The subset of information available to Marshall may, or may not, be representative of all shootings.
"Marshall's data indicates that the .357 Magnum (or whatever cartridge) will be a 90% (or whatever percentage) stopper."
This statement is very much mistaken. Marshall's information is historical, not predictive. It indicates what has happened rather than what will happen. Which brings us to the what I believe is the single largest misconception.
Are you one of the people who have used Marshall's data as a guide when shopping for a defensive pistol and/or ammunition?
I am.
And I've been wrong.
Here is the problem - neither Marshall's data nor anyone else's can be used to predict a single future outcome. Even if we assume that Marshall's data has predictive value (a risky assumption since his information is descriptive in nature rather than predictive), it cannot predict individual outcomes. That's the nature of the world in which we live. Even if we know that a flipped coin will be "heads" 50% of the time, we can't know before hand if the *next* flip of the coin will result in a heads.
[Here I have to disagree. Comparing the potential outcome of a shooting to the potential outcome of a coin flip is not realistic, as there is an exactly 50-50 chance that the coin will land on one of its two sides. However, knowing that the human body reacts badly to being shot (especially in the case of torso shots) it would not be fair to assume that the person has a 50-50 chance of being stopped instantly. Data, especially when it consists of single events with almost always identical outcomes leads us to make the quite reasonable assumption that another single event of the same type is at least, very likely, to have an outcome similar to those of previous similar events. Thus, I think it is not entirely wrong to use the data in a predictive manner - Dale]
And individual outcomes are what most of us are interested in. We may, if we are very unlucky, have to shoot someone in defence of our lives. It's very unlikely that we will ever find ourselves in this circumstance. [Well, that all depends on where you live! In South Africa, with crime, especially violent life-threatening crime, totally out of control, the likelihood of landing up in a situation where you are called upon to protect your life or property is actually very high. - Dale] It's even more unlikely that we will find ourselves in this circumstance more than once.
So what we are preparing for is the once-in-a-lifetime situation where we must shoot to survive. And that is an individual outcome. Which cannot be predicted before it happens.
Knowing this, do I still use Marshall's information when I buy ammunition for defensive use? Yes, I do. Even though I know it's silly. Why? Because I'm human, and completely capable of ignoring unpleasant facts...
--------------------------------------------------------------------------------
Return to the Main Page
------------------
Keith
The Bears and Bear Maulings Page: members.xoom.com/keithrogan
Each time new data is released, there are deletions (and additions one supposes) to old data. Maybe a shooting credited in 91 is found to not fit the criteria - the dude was shot already by another cop, etc.
The following is from Dale Towerts "Stopping Power Page":
Misconceptions and Limitations
by Kyrie Ellis 4 May 1996
There has always been much debate, frequently acrimonious, concerning the ability of any specific pistol cartridge to "stop" an attacker. People have tended to develop a fondness for a particular cartridge, and denigrate all others as being inferior in terms of "stopping power".
At times this debate has almost assumed the character of a religious war, complete with slogans ("They all fall to ball!").
Which is why I like Marshall's information.
For the first time we have information about how pistol cartridges actually work in real life. No "simulated tissue", human cadavers, animals, or war stories. Just information about what has actually happened when people were forced to shoot other people.
Which has left us with another, different, set of problems. How can we use Marshall's information? How do we avoid misusing his information? Which is why I've written this up, and submitted it to the "Stopping Power" page. My intent is to identify the misconceptions people (mostly gun magazine authors) seem to have formed about Marshall's information, and the limitations on the usefulness of that information. The format I've chosen (mostly because I couldn't think of a better one) is a statement commonly made about Marshall's information which is either mistaken or misleading, followed by an explanation of why that statement is mistaken or misleading.
"Marshall's study is scientific."
This statement is mistaken. In order for a study to be scientific, it must follow the scientific method. Which means formally stating a hypothesis, constructing an experiment to disprove that hypothesis, conducting that experiment, and presenting the results for review and replication by other researchers. Marshall did none of these things. He just collected information and published it. In the strict sense of the word, there is nothing "scientific" about Marshall's work. Nor could there be. Conducting an experiment where human test subjects are shot (frequently to death) is not something which can (or should!) be done. Nor would such an experiment have any real world value. Conditions in a laboratory can never duplicate conditions in the field.
"Marshall's study is not scientific."
This statement, while true, is misleading. The problem is that it assumes information must be obtained via experiment to be valid or useful. We don't need to conduct an experiment to determine that fire is hot, or that being shot is bad for our health. Nor is information gained from a scientific experiment necessarily valid or useful. Consider that scientific research once was used to prove that ionising radiation was beneficial to our health and well being...
"Marshall's statistics..."
Any statement which refers to Marshall's information as "statistics" or "statistical" is mistaken. [Er, I must confess to occasionally being guilty here. - Dale] What people refer to as Marshall's "statistics" is really the proportion of people who stopped being aggressive after being shot once in the torso, expressed as a percentage. Unlike ball scores and batting averages, each case in Marshall's study had only two outcomes - a "stopped" or a "not stopped". Events which have only two outcomes are not suitable subjects for statistical study, since they cannot have any of the customary statistical measurements of central tendency (such as mean, median, or mode), or of variation (such as variance or standard deviation). The problem here is that we are so accustomed to seeing statistical data presented as percentages that we automatically assume all percentages are statistical.
"Marshall's sample..."
Any statement which refers to the shootings in Marshall's data base as a "sample" is misleading at best, and mistaken at worst. The word "sample" is generally used to describe a subset of events, taken from a larger set of events, because the whole set of events is too large to be manageable. Samples intentionally exclude qualifying events. Marshall pursued all of the shootings he could. He did not pick and choose from qualifying shootings. His data contains all of the events which met the criteria of one shot to the torso, and to which he had access. The reason that this is an important distinction is that the inclusion of all available information removes any objections to Marshall's information based on claims of "sampling error" - there is no sample. Which is not to say that Marshall's information truly represents the effectiveness of all cartridges. The subset of information available to Marshall may, or may not, be representative of all shootings.
"Marshall's data indicates that the .357 Magnum (or whatever cartridge) will be a 90% (or whatever percentage) stopper."
This statement is very much mistaken. Marshall's information is historical, not predictive. It indicates what has happened rather than what will happen. Which brings us to the what I believe is the single largest misconception.
Are you one of the people who have used Marshall's data as a guide when shopping for a defensive pistol and/or ammunition?
I am.
And I've been wrong.
Here is the problem - neither Marshall's data nor anyone else's can be used to predict a single future outcome. Even if we assume that Marshall's data has predictive value (a risky assumption since his information is descriptive in nature rather than predictive), it cannot predict individual outcomes. That's the nature of the world in which we live. Even if we know that a flipped coin will be "heads" 50% of the time, we can't know before hand if the *next* flip of the coin will result in a heads.
[Here I have to disagree. Comparing the potential outcome of a shooting to the potential outcome of a coin flip is not realistic, as there is an exactly 50-50 chance that the coin will land on one of its two sides. However, knowing that the human body reacts badly to being shot (especially in the case of torso shots) it would not be fair to assume that the person has a 50-50 chance of being stopped instantly. Data, especially when it consists of single events with almost always identical outcomes leads us to make the quite reasonable assumption that another single event of the same type is at least, very likely, to have an outcome similar to those of previous similar events. Thus, I think it is not entirely wrong to use the data in a predictive manner - Dale]
And individual outcomes are what most of us are interested in. We may, if we are very unlucky, have to shoot someone in defence of our lives. It's very unlikely that we will ever find ourselves in this circumstance. [Well, that all depends on where you live! In South Africa, with crime, especially violent life-threatening crime, totally out of control, the likelihood of landing up in a situation where you are called upon to protect your life or property is actually very high. - Dale] It's even more unlikely that we will find ourselves in this circumstance more than once.
So what we are preparing for is the once-in-a-lifetime situation where we must shoot to survive. And that is an individual outcome. Which cannot be predicted before it happens.
Knowing this, do I still use Marshall's information when I buy ammunition for defensive use? Yes, I do. Even though I know it's silly. Why? Because I'm human, and completely capable of ignoring unpleasant facts...
--------------------------------------------------------------------------------
Return to the Main Page
------------------
Keith
The Bears and Bear Maulings Page: members.xoom.com/keithrogan
