Final answer:
The incorrect reason for the 5-to-1 ratio of reported versus substantiated cases of child maltreatment is 'investigations usually find no harm from reports filed by mandated reporters'. Other provided reasons are legitimate, such as the necessity of proof, the potential for false reports, and each instance being counted separately.
Step-by-step explanation:
Among the reasons for the 5-to-1 ratio of reported versus substantiated cases of child maltreatment, the option that is NOT a valid reason is 'investigations usually find no harm from reports filed by mandated reporters'. In fact, mandated reporters such as teachers, law enforcement personnel, and social services staff are trained professionals who report suspected abuse as part of their duty, and their reports are often taken very seriously. The other reasons provided—'each instance is counted, even if it is the same child', 'proof is needed to substantiate a claim', and 'a report may be false or misleading'—are legitimate factors contributing to the disparity between reported and substantiated cases. Reports by mandated reporters lead to investigations, but not necessarily a finding of harm, due to complexities in gathering conclusive evidence or confirmation from victims.