Measure Form

A measure form is the arithmetic form a reading takes: what kind of number it is before anyone asks what it is about. It governs how two readings may be compared and what a change in one of them can mean, because a count and a share that move by the same amount have not moved by the same amount.

Its measure forms— 7

• TotalA count or sum over a period. It grows with volume, so it cannot be compared across periods of different size without saying so.
• RateA count over the population that could have produced it, in the same period. It is stable against volume, which is what makes it comparable where a total is not.
• ShareA part over a whole that is itself measured, rather than over a population acted on. It moves when the whole moves, so a falling share is not always a falling part.
• RatioOne measured quantity over another of a different unit, such as money over outcomes. It answers what a thing costs or returns rather than how often it happens.
• ValueAn amount in the unit the business plans in, carried on one subject rather than aggregated over events. It is the form a forecast can be read against.
• IndexA composite standing built from several underlying readings against stated thresholds. Its movement is interpretable only alongside what went into it.
• ChangeThe movement of another reading between two stated periods. It carries no level of its own, so it cannot be read without the reading it is the change in.

Why it matters

What goes wrong without it, as the commitments that license this kind say it, each standing on its sources.

• Make outcome quality, calculation method and attribution inspectableAn outcome number is only as good as the inputs, exclusions and window that nobody wrote down. Media measurement standards exist because outcome claims circulate detached from their method, and a figure with no stated method cannot be challenged, reproduced or compared against anyone else's. Keeping what a measure means apart from how it is computed is what makes either one reviewable.
  Outcomes and Data Quality Standards · Declaring the Grain · Measuring Visibility in the AI Era · Data-driven multi-touch attribution models · Causally motivated attribution for online advertising · A Comparison of Approaches to Advertising Measurement: Evidence from Big Field Experiments at Facebook · Why Three Exposures May Be Enough · Digital Audience-Based Measurement Standards
• A reading names its unit, and the unit fits its formA number without its unit is not a reading. Metrology defines a quantity value as a number and a reference together, and the unit codes exist because a value that travels without its unit is misread at the far end: a rate and a count that print the same figure have said different things, and percent is a name for the number 0.01, not a kind of thing. This model already fixed a KPI's direction and form as facts in the graph; the unit is the third fact of that family. Declaring which forms a unit fits is what a unit ontology does when it binds units to kinds of quantity, and it turns unit-form agreement from a review into a check.
  International Vocabulary of Metrology: Basic and General Concepts and Associated Terms (VIM), JCGM 200:2012 · ISO 80000-1:2022 Quantities and units, Part 1: General · The Unified Code for Units of Measure, version 2.2 · QUDT Ontologies: Quantities, Units, Dimensions and Data Types, release 2.1 · ISO 4217 Currency codes