Descriptive and process classifications

In Chapter 1, I reiterated Haddon’s point that there is a need to base our science on an understanding of processes rather than description of the phenomenon of interest.  Here is what Haddon said in the introduction to his famous ‘Ten Countermeasure Strategies’ paper:

“An important landmark is reached in the evolution of a scientific field when classification of its subject matter is based on the relevant, fundamental processes involved rather than on descriptions of the appearances of the phenomena of interest. In illustration, a fundamental turning point was reached when the debilitation and progressive susceptibility to bruising resulting from shipboard scurvy could for the first time be classified as the process resulting from a deficiency of consumption of something variously present in fruits and vegetables (much later identified as ascorbic acid, Vitamin C). In fact, such transition from classifications consisting essentially only of a description of appearances, to those based on fundamental processes,  is basic to scientific progress generally; hence, examples abound from the full gamut of scientific concerns”.

I implied that accident theory in practice is more a demonstration of the descriptive approach than the process approach.

This observation applies to the accident classifications we develop. You may recall from the text that classifications are the way in which scientific knowledge is conveyed in the geological and biological sciences and that it is the appropriate means of expressing our knowledge in this field.

It can sometimes be hard to see the difference between process-based and descriptive classifications of ‘accidents’.  As Chapter 1 and Chapter 2 point out, the biological and geological sciences have demonstrated the benefits of process-based classifications in the advancement of the scientific knowledge of a discipline.

In this note, examples illustrate the two different approaches.

It is interesting that we use both descriptive and process-based phrases commonly when talking about injury.

In Occupational Risk Control  the theory used is that the process (assuming that damage occurred or could have occurred) necessarily involves an energy source.  It is interesting that in the second column the nature of this process is made clear.  Energy-damage thinking is not as far from our practice as many think.


Foreign body in the eye

This is a simple description of the Recipient organ and describes the end of the Outcome process that has resulted in damage to it – an impact with a foreign body.  No information is given about the process that gave rise to the presence of the foreign body, nor about the energy form that was involved, which could actually be gravity, chemicals, kinetic energy or even muscular energy (I know of someone who bent down to scrutinise some food while holding a knife upwards in their fist and they pierced their eye ball with it).

Single car crash on a country road

This simple statement describes the recipient and the damage and the location.  It implies nothing about the process that gave rise to it, for example swerving to avoid another car or an animal, a medical condition, falling asleep at the wheel, mechanical failure (tyre blowout) etc.

Manual handling

This term is used to describe a range of body actions involving the handling of something else.  However, the processes involved can be varied and I have seen it used to include the use of muscles and the swinging of limbs, sitting at a chair handling small components, catching something and so on.

Struck by or striking against

This describes the end of two different Outcome processes.  One implies an external object with energy and the other the body’s own energy.


Implies a vertical gravity energised movement.  Note the common use of ‘slip, trip and fall’ is a combination of two (of about 12) possible Mechanisms and an Event.  It is a good example of the thoughtless use of classifications.

Muscle effort
Implies a process involving the use of the muscles to do work.

Noise-induced hearing loss

Explicitly identifies the absorption of noise energy by the ear

Repetitive strain injury

Explicitly identifies the repetitive use of the muscles leading to wear or weakness in the affected tissue

Signal passed at danger

In the rail industry, this class of occurrences is very important.  The classification defines the Event (but not the Mechanism)and as much of the Outcome as it makes sense to include.

Controlled flight into terrain

Used in aviation, this classification implies the nature of the Event (perhaps as loss of situational awareness), but not the Mechanism and the Outcome as an impact with the ground.

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