Aggregation rules can differ by concept level, so ignoring levels distorts measures

Evidence

So in terms of the final measure one would aggregate up from the indicators and then choose some appropriate mathematical operation for the logical AND which then would generate the final quantitative measure. … This example illustrates an extremely common situation, where the structure of the concept or aggregation differs according to the level. This is why the multilevel aspect is critical. Unless one has mapped out the concept and appropriately identified the aggregation implied or concretely given in the conceptualization, one will not get a final numeric measure that accurately reflects the content of the concept. — Gary Goertz, Social Science Concepts and Measurement, 291

Categorization

• SEED: Angle: ‘Your democracy index is lying to you’ — how routinely used composite indices (Polity, Freedom House) average together components their own definitions treat as jointly necessary.