Threshold rules in composite indices are often adopted without explicit justification.

Evidence

The EU uses the same m-of-n strategy to aggregate the secondary-level dimensions to the basic-level “risk of poverty and social exclusion.” If the individual has 1 of the 3 secondary-level dimensions then they pass the threshold and are considered at risk. While I have not searched too hard, I have seen no specific justification for the 3-of-9 rule for material deprivation or the 1-of-3 rule for the basic-level concept of risk of poverty and social exclusion. — Gary Goertz, Social Science Concepts and Measurement, 991

Categorization

• QUESTION: Where did the 3-of-9 and 1-of-3 cut points actually originate — statistical fit, political negotiation, or precedent?