11.5 Quality theme summary
It is important when using agile to distinguish between the quality of a product (defined by quality criteria) and the scope (defined by the products themselves). Some project management philosophies see a reduction in scope as a reduction in quality. PRINCE2 does not see it this way. From the beginning of a project the customer’s quality expectations (and associated acceptance criteria) are set, and this level of quality needs to be maintained. At the end of a project if 10 per cent of the scope is not delivered but the remaining 90 per cent that has been delivered has achieved the desired quality level, then this is seen by PRINCE2 as a reduction in scope, not a reduction in the quality level.
If you do not know how to test a requirement, then assume you have not understood the requirement yet.
Furthermore, and as part of the thinking behind flexing what is being delivered, it is the de-scoping that enables the quality level to be protected and therefore avoids incurring ownership costs (e.g. due to maintenance) throughout the life of the final product.