Pre-Requisites
The Shunt Effect
The last place we want to be finding defects is at the end of the deveopment phase, as the end date looms we enter into an increasingly vulnerable period, defects found at this stage could have impact right across the system affecting analysis, design and implementation. The cost of change at this point is at its highest in the project as numerous stages, apparently complete and signed off have to be re-opened modified and then ratified all over again
With fixed deadlines, as defects increase all that can happen is to increase the working hours of the team, or bring in more people to carry out testing. The former only results in less productivity as people wear out, and the latter causes further delays as new starters need training in the product under test.
Another more serious impact is known as the Shunt Affect, as each phase of the project is delayed the remaining phases "shunt" along the project timeline eating into the most important phase of the project, that of testing.
The immediately effect of the shunt is that testing teams are given descreasing time to complete the same amount of work, leading to either reduced quality as short cuts are taken, or constant descoping as the deadline looms leaving the product with a huge backlog of wasted untested code/features.
Next Steps