1. The fastest way of changing from one system to another
2. Phased
2.1. ADVANTAGES
2.1.1. The company staff is trained gradually, not intensively, which makes the re-qualification process easier.
2.1.2. Easier to identify where (in which phase) system errors occur.
2.1.3. It is possible to replace a certain part of the new system with that of the old system in case of system fails.
2.2. DISADVANTAGES
2.2.1. Expensive
2.2.2. Takes a Long time
2.2.3. Not multitasking(Only suitable for systems that can be split into separate parts)
2.2.4. Demands testing each phase separately
2.3. DEFINITION
2.3.1. Implementing the new system step-by-step, testing only one of its phases at a time.
3. Direct implementation method
3.1. Advantages
3.1.1. The new system can be used immediately after installation
3.1.2. Cheap
3.1.3. Less chance of the new system being faulty
3.2. Disadvantages
3.2.1. High risk of losing data
3.2.2. As the old system is completely deleted, there is nothing to go back if the new one fails.
3.2.3. Staff have to be trained and it takes a long time.
3.2.4. The all old data needs to be uploaded to a new database.
4. Parallel method
4.1. For some time, old and new systems work alongside each other
4.1.1. advantages:
4.1.1.1. no data will be lost. If the new system fails, the old one is saved
4.1.1.2. effective way to test the new system
4.1.1.3. staff can get used to the new system over some time
4.1.2. disadvantages:
4.1.2.1. much more expensive. Uses a running cost of two systems.
4.1.3. suitable situation: human resource management, job placement, etc.
5. Pilot
5.1. Running a new system only in one part of company and if it work correctly, implement it to another parts
5.1.1. Advantages
5.1.1.1. If system doesn't work correctly, it will affect only on one part of the company
5.1.1.2. It is cheaper than another runnings, because that method includes only one part of the company
5.1.2. disadvantages
5.1.2.1. it takes longer to implement system
5.1.2.2. if system fails, chosen department might lose data