The document discusses how success and failure in sociotechnical systems are subjective and depend on the perspective of the observer. It notes that sociotechnical systems are non-deterministic due to human factors and system changes over time. Different stakeholders may have conflicting views of what constitutes success or failure based on their goals. The document concludes that failures are normal and inevitable in complex systems due to technical limitations and differing stakeholder perspectives.

1. Success and failure
Ian Sommerville
Success and failure in sociotechnical systems, 2013
Slide 1

2. Non-determinism
•
A deterministic system is one where a given
sequence of inputs will always produce the same
sequence of outputs.
•
Software systems are deterministic;
•
Systems that include humans are non-deterministic
Success and failure in sociotechnical systems, 2013
Slide 2

3. • A socio-technical system will not always
produce the same sequence of outputs
from the same input sequence
Success and failure in sociotechnical systems, 2013
Slide 3

4. • Human operational behaviour
– People do not always behave in the same
way
– Their actions are determined by a range of
internal and external factors
Success and failure in sociotechnical systems, 2013
Slide 4

5. • System changes
– System behaviour is unpredictable because
of frequent changes to hardware, software
and data in seperately managed systems or
components
Success and failure in sociotechnical systems, 2013
Slide 5

6. Subjective behaviour
• Whether or not a system has is effective
in ‘doing its job’ depends on the
observer of a system
Success and failure in sociotechnical systems, 2013
Slide 6

7. • Complex socio-technical systems serve
different stakeholder groups, which may have
conflicting objectives
• Behaviour that is effective for one group, may
be ineffective for another
Success and failure in sociotechnical systems, 2013
Slide 7

8. Success criteria
•
Complex systems are developed to address ‘wicked
problems’ – problems where there cannot be a
complete specification.
•
Different stakeholders see the problem in different
ways and each has a partial understanding of the
issues affecting the system.
Success and failure in sociotechnical systems, 2013
Slide 8

9. • Success is a judgment and cannot be
objectively measured.
• Success is judged using the effectiveness of
the system when deployed rather than judged
against the original reasons for procurement.
Success and failure in sociotechnical systems, 2013
Slide 9

10. Conflicting views of success
• A medical information system may be
designed to support multiple, conflicting
goals
– Improve quality of care.
– Provide better information and care costs
and so increase revenue.
Success and failure in sociotechnical systems, 2013
Slide 10

11. Success and failure in sociotechnical systems, 2013
Slide 11

12. •
Fundamental conflict
–
–
•
To satisfy reporting goal, doctors and nurses had to provide
additional information over and above that required for
clinical purposes.
They had less time to interact with patients, so quality of care
reduced. System was not a success.
However, managers had better reports
–
System was a success from a managerial perspective.
Success and failure in sociotechnical systems, 2013
Slide 12

13. What is failure?
•
A failure is ‘a deviation from a specification’.
•
An oracle can examine a specification, observe a
system’s behaviour and detect failures.
•
Failure is an absolute - the system has either
failed or it hasn’t
Success and failure in sociotechnical systems, 2013
Slide 13

14. Success and failure in sociotechnical systems, 2013
Slide 14

15. A hospital system
•
A hospital information system is designed to maintain
information about available beds for incoming
patients and to provide information about the number
of beds to the admissions unit.
•
It is assumed that the hospital has a number of empty
beds and this changes over time. The variable B
reflects the number of empty beds known to the
system.
Success and failure in sociotechnical systems, 2013
Slide 15

16. •
Sometimes the system reports that the number of
empty beds is the actual number available;
sometimes the system reports that fewer than the
actual number are available .
•
When the system reports that an incorrect number of
beds are available, is this a failure?
Success and failure in sociotechnical systems, 2013
Slide 16

17. • The percentage of system users who
considered the system’s incorrect
reporting of the number of available
beds to be a failure was 0%.
Success and failure in sociotechnical systems, 2013
Slide 17

18. Bed management system
•
Mostly, the number did not matter so long as it was
greater than 1. What mattered was whether or not
patients could be admitted to the hospital.
•
When the hospital was very busy (available beds =
0), then people understood that it was practically
impossible for the system to be accurate.
Success and failure in sociotechnical systems, 2013
Slide 18

19. Failure is a judgement
• Specifications are a gross simplification of
reality for complex systems.
• Users don’t read and don’t care about
specifications
Success and failure in sociotechnical systems, 2013
Slide 19

20. •
Whether or not system behaviour should be
considered to be a failure, depends on the observer’s
judgment
•
This judgment depends on:
–
The observer’s expectations
–
The observer’s knowledge and experience
–
The observer’s role
–
The observer’s context or situation
–
The observer’s authority
Success and failure in sociotechnical systems, 2013
Slide 20

21. Failures are inevitable
• Technical reasons
– When systems are composed of opaque and
uncontrolled components, the behaviour of these
components cannot be completely understood
– Failures often can be considered to be failures in data
rather than failures in behaviour
Success and failure in sociotechnical systems, 2013
Slide 21

22. Success and failure in sociotechnical systems, 2013
Slide 22

23. • Socio-technical reasons
– Changing contexts of use mean that the
judgement on what constitutes a failure changes
as the effectiveness of the system in supporting
work changes
– Different stakeholders will interpret the same
behaviour in different ways because of different
interpretations of ‘the problem’
Success and failure in sociotechnical systems, 2013
Slide 23

24. Conflict inevitability
• It is usually impossible to establish a set of
requirements where all stakeholder conflicts
are resolved
• Therefore, successful operation of a system
for one set of stakeholders will inevitably
mean ‘failure’ for another set of stakeholders
Success and failure in sociotechnical systems, 2013
Slide 24

25. Normal failures
•
‘Failures’
are not just catastrophic
events but normal, everyday system
behaviour that disrupts normal work and
that mean that people have to spend
more time on a task than necessary
Success and failure in sociotechnical systems, 2013
Slide 25

26. A system failure occurs when a direct or
indirect user of a system has to carry out
extra work, over and above that normally
required to carry out some task, in
response to some inappropriate or
unexpected system behaviour
Success and failure in sociotechnical systems, 2013
Slide 26

27. Summary
•
Success and failure are not absolute but depend on
the judgment of the observer
•
It is impossible to reconcile all conflicts in a complex
STS – therefore some stakeholders may consider
system behaviour as ‘failure’
•
Failures are normal and inevitable in system
operation
Success and failure in sociotechnical systems, 2013
Slide 27