Can you ever test or validate your performance management system "completely?" Should you even try?
In the software development business, words like "test," "verify" and "validate" do have specific, different meanings, depending upon the context in which they are used. Let's explore these, in the context of what it might mean to "completely" "prove" that an organization's information systems performance measurement and management plans, programs and procedures, tools and techniques, really do work correctly and effectively.
First, look up those concepts (test, verify, validate, prove), in the literature on systems development, test, acceptance, verification and validation (in other words, do not just use a dictionary!). You may also need to go beyond what's presented in the textbook, to understand the overall process of performance measurement and management. Let these inquiries help you frame up and present your arguments with respect to this topic.