Introduction p 2: What
CASSM offers
CASSM helps the analyst to think about system and user representations
in a structured and rigorous way.
Example
We applied CASSM to London Ambulance Service's call-handling. We found
two different concepts of "call":
- emergency call (someone dialling '999' to report an incident);
this concept has attributes such as caller line identifier, nature
of incident as reported, caller location, etc.
- incident with properties
such as number of casualties, location, type of incident, etc.
Incidents
in public places, such as road traffic accidents or train crashes,
can generate dozens or even hundreds of emergency calls for a single incident.
PROBLEM ..... at that time the ambulance controllers had a computer system that forced
them to process emergency calls rather than incidents, requiring them to
specify which resources (ambulances etc.) had been deployed to
each phone call. So they had to repeat identical information dozens or hundreds of times. At a busy time, this might
delay their response to some other incident ...
Obvious with hindsight, of course. But it wasn't obvious at the
time: it was the structured, rigorous CASSM analysis that helped tease these two concepts
apart.
In more detailed working, CASSM can support thinking about structural
misfits such as viscosity ... but that topic demands too much
detail for an overview, and is left to the tutorial.
[ next page : the 'misfit' concept]
This page last modified
26 February, 2010
by Ann Blandford
|