4. Phased strategy
This is an useful strategy for systems that are made up of smaller sub-systems. The idea is to introduce each sub-system one at a time.
For example, module 1 in the picture above is activated in the system. This replaces part of the existing system. The sub-system is thoroughly tested by the users to ensure that there are no serious issues with it.
Then the next phased introduction continues by loading module 2 into the system. The same thing happens again - problems and issues are identified and resolved before carrying on.
The main disadvantage of this strategy is that it may not be possible to sub-divide the system in this way. Another issue is that it may take a long time to roll out every module. A more subtle problem may be that a fault in 'module 2' causes an unexpected fault in module 1 that previously worked fine.
Its attraction is that it offers very controlled management of risk. If a module does not work properly, then the older part of the system can be re-instated without too much disruption to the organisation.
challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Phased implementation of an IT system