The general response of PRINCE2's authors to criticism has been to point out that the methodology is scalable and can be tailored to suit the specific requirements and constraints of the project and the environment. This strong emphasis on tailoring has led some users to complain that PRINCE2 is unfalsifiable, i.e. it is impossible to tell whether PRINCE2 "works" or constitutes "best practice" if any problems encountered with a project can be blamed on inappropriate application of PRINCE2 rather than on PRINCE2 itself.