Most people looking for radon credentials are professionals in home inspection, plumbing, HVAC, or similar vocations who have successfully passed other vocational exams and assume the radon exam is a similar measure of competency.
However, psychometric assessments objectively measure the understanding of a subject matter in relation to the candidate’s ability to use mental reasoning, skill, intelligence, personality traits, motivations, and interests. In other words, psychometric exams are often described as being riddled with ‘trick’ questions; as opposed to competency/skill tests which simply determine to what extent a candidate possesses a particular skill or capability.
Radon is not your garden variety subject matter. In contrast, radon science is a healthy mix of nuclear physics, building performance, construction and trades skill, and environmental science. The exam success rate is low for someone without extensive practical radon experience or subject matter knowledge.