| Direct
changeover
|
The old system is stopped and the following day the
new system is used.
This could be disastrous if there are errors in the new
system!
|
| Parallel
running
|
The old system and the new system are run together
for a period of time. The old system is stopped only when it is
certain that the new system is running correctly.
Advantage : no
disasters if there are errors in the new system
Disadvantage : a
lot of duplication of work.
|
| Piloting
|
The new system could be tried by part of the
company - eg one branch.
If all goes well, then the rest of the company can change to
the new system
|
| Phased
change |
Part of the new system is used, and when all
problems have been solved and it works then another part is
implemented and so on...
|
