A large share of analytical errors arises not at the analysis stage but earlier — when indicators that merely share a name are consolidated into one table. “Number of applications” includes repeat submissions in one agency and excludes them in another; “average processing time” is counted in calendar days here and in working days there.
The indicator passport
The minimum set of fields without which an indicator cannot be considered defined: a verbal definition, calculation formula, unit of measurement, source of primary data, frequency, cut-off date, responsible unit and the rule for handling missing values.
Introducing passports almost always exposes discrepancies the reporting parties did not suspect. It is an uncomfortable but necessary step: without it, any comparison between organisations remains a comparison of different quantities.