Information-Source Inventory Matrix¶
Mapping artifact — instantiates Information Set Specification and Completeness Verification
Maps information sources to availability, timing, actor access, cost, reliability, and expected incorporation pathway.
The Information-Source Inventory Matrix is the front-end specification the whole verification hangs on: a static table, built before any statistical test runs, with one row per information source and columns for when it became available, who could access it, what it costs to obtain, how reliable it is, and through which channel it should enter the signal. Its defining move is separating the specification of the information set from any measurement of the signal. It never touches prices or returns; it disciplines the claim by writing down, in advance, exactly which information is in scope, whether it was genuinely available at the relevant time (guarding against hindsight), and which information is excluded because it is private, illegal, or unknowable. A completeness test with no matrix behind it is an untethered opinion; the matrix is what stops "the market knows everything" from quietly redefining "everything" after the results come in.
Example¶
A real-estate investor wants to test whether prices in a specific neighborhood already reflect the information that matters. Before pulling a single comp, she builds the matrix. Rows: the MLS listing feed, county permit and zoning filings, a proposed transit-line hearing schedule, school-rating updates, and the local-broker grapevine. Columns force the hard questions. When available? — the zoning docket posts publicly weeks before it trends locally; the grapevine leads the docket by days. Who can access? — MLS is agent-gated, permits are public-but-obscure, the grapevine is locals-only. Cost? — permit records are free but take hours to parse. Reliability? — grapevine high-variance. Expected pathway? — each should enter prices through comparable sales and broker pricing, but only after someone actually reads and acts on it. The register also lists what's excluded: a pending private deal she legally cannot use. The finished matrix is not a verdict; it is the scoped, hindsight-proof boundary — these sources, available to these actors, by these dates — that every later test must be judged against.
How it works¶
- Enumerate sources, one per row. Every candidate information source in the intended set gets a line, so nothing is silently assumed in or out.
- Timestamp true availability. Each row records when the source actually became knowable to the relevant actors — not when it became obvious in hindsight.
- Score access, cost, and reliability. Columns capture who could reach the source, at what cost, and how trustworthy it is, exposing information that is available in principle but not to the public.
- Name the expected pathway. Each source is tagged with the channel by which it should reach the signal, so later tests know what incorporation would even look like.
Tuning parameters¶
- Row granularity — one line per feed versus per field. Finer rows surface hidden sub-sources but bloat the matrix and invite false precision.
- Availability strictness — how conservatively "available at the time" is judged. Strict timestamps kill hindsight but may exclude information that diligent actors truly had.
- Access taxonomy — how many access tiers you distinguish (public / subscriber / local / specialist / insider). More tiers sharpen the efficiency form being claimed but demand more evidence per row.
- Reliability weighting — whether unreliable sources are down-weighted or excluded outright, trading coverage against noise.
When it helps, and when it misleads¶
Its strength is that it makes the information set pre-committed and legible, which is the single most important guard against the archetype's headline failure — leaving the set undefined and laundering the boundary after an anomaly appears. It also cleanly separates public from costly and private information, so a claim can be scoped to the right form of efficiency. Because information is genuinely costly to gather and process[n1], the cost and access columns are not bureaucratic detail — they are the difference between "reflected in prices" and "reflected in prices for those who paid to know."
Its failure mode is the comfortable illusion of completeness: a tidy matrix can feel authoritative while omitting whole categories of information nobody thought to list, and it says nothing about whether any listed source actually entered the signal — only that it could have. The guarding discipline is to treat the matrix as a living register, revisited when new feeds or access regimes appear, and to remember it is the setup for verification, never the verdict.
How it implements the components¶
information_set_boundary_statement— the scope column declares, source by source, which information classes are in and which are out.available_information_inventory— each row's availability timestamp records what was actually knowable, and when, so tests can't use hindsight information.incorporation_pathway_model— the pathway column names the expected channel (comparable sales, broker pricing, disclosure) by which each source should reach the signal.excluded_information_and_access_register— the access and exclusion columns log who can reach each source and which sources are barred (private, illegal, unknowable).
It does NOT measure the signal at all — no response test, no residual, no drift; whether a listed source was in fact incorporated is decided by Event-Study Information-Response Test and Abnormal-Return / Residual Model, via response_completeness_test and residual_opportunity_probe. Its nearest twin is the microstructure probe: the matrix catalogs sources and access on paper before any test, whereas Market-Microstructure Order-Book Probe reads live quotes, depth, and order flow to see whether the information actually surfaces.
Related¶
- Instantiates: Information Set Specification and Completeness Verification — provides the pre-committed, hindsight-proof information-set boundary the tests are scored against.
- Sibling mechanisms: Event-Study Information-Response Test · Post-Announcement Drift Analysis · Abnormal-Return / Residual Model · Arbitrage Opportunity Scan · Market-Microstructure Order-Book Probe · Lagged-Response Regression · Cross-Market Information-Leakage Check
Editorial Notes¶
Form Classification¶
Form family: Representation, Specification & Plan
Rationale: Information-Source Inventory Matrix operates as a non-executable information artifact that externalizes static or prospective structure because it maps information sources to availability, timing, actor access, cost, reliability, and expected incorporation pathway
Independent corroboration: The frozen evidence defines Information-Source Inventory Matrix as 'Maps information sources to availability, timing, actor access, cost, reliability, and expected incorporation pathway', so its operative form is Representation, Specification & Plan.
Review outcome: Independent reviewer agreement; high confidence.
Origin Attribution¶
Primary origin: Library & Information Science
Origin pattern: Cross-disciplinary synthesis
Present-day reach: Multi-domain
Rationale: Systematic inventory of sources, access, provenance, timing, and reliability is rooted in information-resource organization and retrieval.
Related originating lineages:
- Data Science & Analytics — Data lineage and source-quality practice materially shape the matrix's incorporation and reliability fields.
- Economics & Finance — Economics of costly information materially explains why acquisition cost and access cannot be omitted.
Review resolution: Both independent reviews place the primary lineage in library_information_science. The queued differences (reported_ambiguity, alternate_origin_disagreement) concern secondary metadata rather than primary provenance. The final retains data_science, economics_finance only where a reviewer supplied a formative-lineage rationale; this does not convert downstream applicability into origin. origin_mode=cross_disciplinary_synthesis because the entry's present form deliberately composes methods from the documented lineages. domain_reach=multi_domain records application breadth separately from provenance.
Attribution caveat: The specific multi-attribute matrix appears encyclopedia-formulated around established source-audit concerns.
Encyclopedia synthesis: The exact catalogued form synthesizes established practice rather than reproducing a single standard historical label.
Review outcome: Reconciled after independent review; medium confidence.
Notes¶
[n1] The Grossman-Stiglitz paradox: if prices perfectly reflected all information, no one would be paid to gather costly information, so prices cannot be fully informationally efficient — there must be a return to being informed. This is why the matrix's cost and access columns are load-bearing, not decorative. ↩