tegwick
f2d216af53
§10.3 now accepts a consumer record that validates against the live catalog; resource-control's backup restatement is that proof. ITC-GOV gains EvidenceBasis in tiers (invoiced and measured are peers) and ITC-CAP requires it on every consumption row (CAP-R10).
192 lines
8.3 KiB
Markdown
192 lines
8.3 KiB
Markdown
# Demand: Evidence Basis — how a quantity was obtained, and how far a conclusion may be trusted
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**Status:** accepted (canon 0.4.0)
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**Date:** 2026-08-15
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**Source:** resource-control (consumer), domain `financials`
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**Owner:** **ITC-GOV** (Evidence), imported by `ITC-CAP` `CapabilityConsumption` (CAP-R10)
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**Requested by:** info-tech-canon, in reply to the ITC-CAP restatement, 2026-08-15
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**Consumer implementation:** `resource-control/tools/basis.py`, `docs/evidence-basis.md`
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**Workplan:** `ITC-WP-0015`
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**Catalog:** `infospace/models/governance/evidence-basis.yaml`
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---
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## Demand signal
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ITC-GOV §11.34 defines **Evidence** as "information used to support a claim",
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with examples that are all *artifact kinds*: a log extract, a scan result, a
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test result, a deployment record. §11.35 defines an **Assertion** as a claim
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that something is true, supported by evidence.
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Nothing in the canon says **how a quantity was obtained**, and therefore nothing
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bounds how far a conclusion computed from it may be trusted.
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That is a different question from which artifact supports a claim. An artifact
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can be impeccable while the number inside it is a guess. A consumer reading two
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numbers of the same shape — `7.35` and `60.00` — cannot tell that one is a
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published price and the other is an assumed hour count multiplied by an assumed
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rate, and the canon currently gives it no way to say so.
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## Why this cannot stay private to one consumer
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`resource-control` has implemented and is running this. We are filing rather
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than keeping it because the same argument info-tech-canon accepted for
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`CapabilityConsumption` applies unchanged: a private vocabulary diverges the
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moment a second repository reports evidence-bearing quantities.
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It is already wanted in three places on the consumer side alone — capability
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consumption rows, monthly actual observations, and threshold evaluations. That
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breadth is also why the concept should **not** live in ITC-CAP: it is not about
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capabilities. It is about quantities, wherever they occur.
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---
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## Proposed concepts
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### `EvidenceBasis`
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A closed, ordered vocabulary naming how a single quantity was obtained.
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| Basis | Meaning |
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|---|---|
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| `invoiced` | Taken from an authoritative financial record |
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| `measured` | Directly observed from the authoritative system |
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| `quoted` | Stated by a provider or counterparty in a citable source |
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| `derived` | Computed from other values by a stated rule |
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| `projected` | Interpolated between, or extrapolated beyond, observations |
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| `estimated` | Human judgement, neither observed nor computed |
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| `assumed` | A modelling constant chosen by the author |
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| `unknown` | No value exists |
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`invoiced`, `measured`, and `quoted` are **evidenced**: they assert an observed
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or contracted fact. Everything below is inference.
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**On `invoiced`.** Per info-tech-canon's own instruction, this names a fin-hub
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fact rather than originating one. The basis says only *where a value came from*;
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it does not define booked-cost, tax, or currency semantics, which stay with the
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financial authority under its own exchange contract.
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**Strength is a tier, not a total order.** `invoiced` and `measured` are peers.
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An invoice is authoritative for a payment and a measurement is authoritative for
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a quantity; neither outranks the other outside its own domain. The consumer's
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first implementation got this wrong by using a strict list order, and corrected
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it — `weakest(["invoiced", "measured"])` must not imply a difference that does
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not exist.
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### `derived_from` and the propagation rule
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> **A derived value is only as strong as the weakest value it was computed from.**
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This is the rule that earns the vocabulary its place. Without it, arithmetic
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launders assumptions: a two-decimal euro figure reads like a measurement when it
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is an assumed hour count times an assumed rate.
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A `derived` value carries `derived_from`, the values it was computed from, and
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resolves to the weakest of them, recursively. Derivation is not penalised in
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itself: GB computed from measured bytes resolves to `measured`.
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### `unknown` carries no quantity
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A value with basis `unknown` MUST NOT carry a quantity, and MUST name the gap
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and the party who owns it. A value with any other basis MUST carry a quantity.
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Zero means "measured and none"; unknown means "not measured". Both directions
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should be enforced, because the failure mode runs both ways — a missing amount
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silently read as zero, and a zero mistaken for an absence.
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### `proxy_for`
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An orthogonal qualifier: the value is a genuine measurement of a *different*
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quantity than the one being reasoned about. It does not weaken the measurement;
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it weakens the inference drawn from it. A shared-database allocation driver may
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measure bytes precisely while one of those databases has never recorded a
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transaction.
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### `DecisionGrade`
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A rollup over the values a conclusion rests on — an **Assertion** whose strength
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is bounded by its weakest supporting value.
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| Grade | Condition |
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|---|---|
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| `evidenced` | Every load-bearing value is invoiced, measured, or quoted |
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| `projected` | The conclusion rests on values projected from observations |
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| `indicative` | The conclusion is no stronger than an estimated or assumed value |
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| `insufficient` | At least one load-bearing value is unknown |
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This is the seam to existing ITC-GOV vocabulary: Evidence supports an Assertion;
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a DecisionGrade states how far that support actually reaches.
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---
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## Worked evidence from the consumer
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The mechanism was applied to the consumer's own most consequential decision —
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the provider selection that produced its backup resource, a €29.14 per month
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difference stated to the cent:
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```
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by_basis {quoted: 1, projected: 1, assumed: 2}
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weakest assumed
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evidenced_ratio 0.25
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grade indicative
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```
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One of four load-bearing values is evidenced. The two labour figures — the ones
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that actually inverted the provider ranking — are each `derived` from an
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`assumed` hour count and an `assumed` rate, so both resolve to `assumed`.
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The finding did not overturn the decision: the direction is robust under any
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plausible rate. It did establish that the *magnitude* is a model output rather
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than a measurement, and it identified the cheapest way to strengthen it —
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record real operator hours, not refine the arithmetic.
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A mechanism whose first act is to qualify its author's own headline number is
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behaving correctly.
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---
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## Proposed placement
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**Owner: ITC-GOV.** `EvidenceBasis`, `derived_from` and its propagation rule,
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the unknown rule, `proxy_for`, and `DecisionGrade` sit beside Evidence,
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Assertion, and Attestation in §11.34–11.36. They describe the epistemic status
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of information, which is ITC-GOV's ground.
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**Import: ITC-CAP.** `CapabilityConsumption` gains an evidence basis per row.
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It already distinguishes unknown from zero, which is the same discipline applied
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to presence; basis applies it to the values that *are* present. `CAP-R8` would
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be joined by a rule that a consumption row declares its basis.
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**Also imports:** ITC-OBS (a measurement is `measured`; a modelled series is
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`projected`), and any model carrying quantities that consumers compare.
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**Avoid:** defining this only in ITC-CAP. It is not about capabilities, and
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scoping it there would force a second, incompatible vocabulary the first time a
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non-capability quantity needs grading.
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---
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## Success criteria
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1. A closed basis vocabulary with tiers, not a spurious total order.
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2. A stated propagation rule for derived values, computable and testable.
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3. Unknown carries no quantity and names its gap and owner; zero is a
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measurement.
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4. `proxy_for` expressible and orthogonal to strength.
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5. Decision grades defined against existing Assertion semantics.
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6. `CapabilityConsumption` imports the basis without ITC-CAP owning it.
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7. `resource-control` can drop its private vocabulary in favour of the canon's
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without changing any recorded value.
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---
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## Non-goals
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- Booked-cost, tax, or currency semantics. `invoiced` names a financial fact;
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it does not define one.
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- A confidence interval, probability, or statistical error model. Basis is
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categorical provenance, not quantified uncertainty. A value may be `measured`
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and still be a single noisy sample — age and sample size are separate
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qualifiers and the canon should not conflate them with basis.
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- A data-quality scoring or maturity scheme for datasets.
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- An automated inference of basis. It is declared by the author of the value.
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