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 School Improvement:  Variation
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There is always variation. Forest Gump put is more succinctly but less politely!
            -Every system & process exhibits variation


Variation leads to waste, disruption, adjustment, the need for inspection & rework.All processes exhibit variation arising from two kinds of causes:

  • Special causes (not arising from the process): These causes are external and beyond the scope of the process. In schools staff illness may cause a variation in the delivery of a particular program. Feuding between families may cause problems in the playground or classroom. Wherever possible these causes should be identified and eliminated. Sometimes it is possible to take action to prevent or minimise the impact of familiar special causes. This is referred to as 'deep coping' in the literature. Much of the work done in creating supportive school environments is done for this purpose. As indicated above, prevention is better than rework. Counter measures need to be understood as rework. It is realistic to acknowledge that the complexity of schools is such that schools need to have the capacity to deal with the unforseen
  • Common causes (inherent in the processes): These causes may be because of 
    inappropriate sequencing of activities
    inappropriate assignment of tasks
    gaps in the process or,
    unnecessary steps included in the process. 
    Variation from common causes can to be reduced by improving the process, ie, addressing the above possibilities
    It is important to know (and not just guess) the actual causes of variation in order to reduce them and thus increase savings, efficiency and effectiveness. Changing a process to counter a special cause adds unnecessary complexity and increases the need for training, inspection, dependence,... Process improvement generally results in simplicity, clarity, confidence, and reduces the need for inspection and rework.
    The savings may include financial benefits as waste is reduced and benefits increased. Just as importantly the benefits are likely to include reduction in stress levels and a greater sense of well-being. The quality if the achievements will be complemented by improvements in the quality of life in most instances. 
  • Plan-Do-Study-Act focuses on reducing variation in the process. It is the process which is studied rather than the outcomes. The starting point is to 
    identify the steps in the process
    distinguish between special and common causes
    address the causes of variation as appropriate
    act to improve the process (if done properly improved & more consistent outcomes will follow). 
    Action: Change from frequent innovation to continuous improvement 

In addition we are considering two other kinds of variation 

  • variation within processes in the system and
  • variation in outcomes ie, variation from the goals and purposes

Since variation in outcomes is deemed to be so importnat it is wise to consider the question: 'What is it that outcomes come out of?'

The answer is: 'Outcomes come out of processes!!' 

Therefore to reduce variation in outcomes one should attend to the processes involved:

  • stablise the processes then
  • improve the processes (reduce variation & improve the outcomes)
  • which reduces costs and maximises benefits


There are two causes of variation
            - Special causes come from outside the system
            - Common causes are inherent in the system

Tampering (changing the system without proper consideration) is a familiar and useless special cause arising from well meaning ignorance on the part of people working in the system.
Quality attends to variation in processes & systems!
- Variation impedes people's capacity to do high quality work 
- Variation is costly because it contributes to uncertainty, rework, the need for inspection,
- Variation is managed from data 
- Problems are unacceptable variations
Quality reduces variation in processes & systems!!!
- Collect & organise data
- Make data freely available
- Identify types of variation
- Respond according to type
Information makes people more responsible and effective.

Responding to causes of variation
- Special cause variation: apply contingency arrangements - do not change the system!
- Common cause variation: improve the system to reduce the causes of variation