Value of Knowledge-Based versus Competence-Based Certification
The basic difference between knowledge-based and competence-based certification is that while knowledge is measured against a standard knowledge base, competence-based certification must evaluate how competent the individual is in applying that knowledge, and skills, in the actual workplace.
Knowledge is defined in a body of knowledge and the standard is applied using a test. Knowledge testing only examines and measures a candidate's understanding of the vocabulary, the body of knowledge as documented, and some practices. The ability to perform to an acceptable level of proficiency is not determined and can only be assumed. That's because candidates taking knowledge based certification exams depend primarily on knowledge recall. However, from the examiners perspective, assessment is less subjective so that the reliability and validity of knowledge testing through written exams is easier to maintain.
On the other hand, competence is a broader standard because competence-based certification infers a candidate's ability to actually perform project management tasks at a given level. It encompasses both knowledge of the subject and the necessary skills to apply that knowledge, and also attitude. For example, a competence-based assessment may include a performance assessment based on a sample of a candidate's work and experience. Compared to knowledge-based certification, performance-based certification gives everyone a greater degree of assurance that a certified individual will, in fact, be able to accomplish responsibilities and tasks to the given standard. However, reliability and validity are somewhat more difficult to maintain.
Thus the relative value of Competence-based certification is significantly greater than knowledge-based certification.