Aggregating heterogeneous indicators into one scale is a critical, under­examined step

Evidence

A key methodological issue involves the fact that one starts from the bottom with the indicators and aggregates upward to get the final numeric value for the concept. This means taking a variety of indicators with different scales and different features and then normalizing or standardizing them onto the same scale; here it will always be [0, 1]. This is a hugely critical operation that is often done without much reflection. — Gary Goertz, Social Science Concepts and Measurement, 182

Categorization

• XREF: Echoes the measurement/aggregation problems in the Milgrom law-merchant and diamond-market pieces, where institutional measures are built from varied proxies.