This document provides the complete technical specification governing IBT certification methodology, statistical framework, governance architecture, and appeals procedure. Intended for external auditors, accreditation reviewers, and expert stakeholders.
This specification defines the complete methodology, governance, and operational procedures governing IBT (International Bureau of Trust) certification. It constitutes the authoritative reference for all assessment activities and supersedes all prior versions.
IBT certification is a third-party attestation that a business's verified client satisfaction rate satisfies a published statistical threshold, as determined by hypergeometric acceptance sampling applied to identity-confirmed client responses. IBT certification is not a warranty, not a complaint resolution mechanism, and not an endorsement of any specific product or service.
Every IBT fee and industry classification derives from three parameters: Industry Impact (I), client count band (N), and Contract size multiplier (C). This framework governs both pricing and the assigned tier label visible in the IBT directory.
IBT uses the hypergeometric distribution — not the binomial or normal approximation — because sampling is conducted without replacement from a finite, known population. The hypergeometric distribution is exact for this scenario and is more conservative than the normal approximation for small-to-medium N.
The proportional floor prevents mathematically-valid but practically-thin samples for large N. For N ≤ 500: floor = 0. For 500 < N ≤ 10,000: floor = ⌈0.05N⌉. For 10,000 < N ≤ 100,000: floor = ⌈0.03N⌉. For N > 100,000: floor = ⌈0.01N⌉.
IBT tightens both producer and consumer risk as N increases. This reflects that larger businesses with more clients should face more demanding statistical evidence requirements. The schedule is symmetric (α = β at all bands).
| N (client count) | α (producer risk) | β (consumer risk) | Rationale |
|---|---|---|---|
| ≤ 100 | 10% | 10% | Small populations; minimal prior data |
| 101 – 200 | 8% | 8% | Growing client base |
| 201 – 500 | 6% | 6% | Established practice |
| 501 – 1,000 | 5% | 5% | Substantial client base |
| 1,001 – 5,000 | 4% | 4% | Regional/multi-location |
| 5,001 – 10,000 | 3% | 3% | Large established firm |
| 10,001 – 100,000 | 2% | 2% | Enterprise |
| > 100,000 | 1% | 1% | National/multinational |
The following table shows canonical (N, n, c) values derived by the algorithm. The proportional floor is shown separately; the operative n is max(n_hyper, floor).
| N | n (hyper) | n (floor) | n (operative) | c | Backstop ⌈10%×N⌉ | α=β |
|---|---|---|---|---|---|---|
| 2 | 2 | — | 2 | 0 | 1 | 10% |
| 5 | 3 | — | 3 | 0 | 1 | 10% |
| 10 | 8 | — | 8 | 1 | 1 | 10% |
| 15 | 9 | — | 9 | 1 | 2 | 10% |
| 25 | 13 | — | 13 | 2 | 3 | 10% |
| 50 | 19 | — | 19 | 3 | 5 | 10% |
| 100 | 24 | — | 24 | 4 | 10 | 10% |
| 200 | 29 | — | 29 | 5 | 20 | 8% |
| 500 | 35 | — | 35 | 6 | 50 | 6% |
| 1,000 | 50 | 50 | 50 | 9 | 100 | 5% |
| 2,000 | 100 | 100 | 100 | 15 | 200 | 4% |
| 5,000 | 250 | 250 | 250 | 33 | 500 | 4% |
| 10,000 | 500 | 500 | 500 | 63 | 1,000 | 3% |
| 100,000 | 3,000 | 3,000 | 3,000 | 334 | 10,000 | 2% |
| 1,000,000 | 10,000 | 10,000 | 10,000 | 1,000 | 100,000 | 1% |
Standing thresholds: Bronze = n, Silver = ⌈1.5n⌉, Gold = ⌈2.0n⌉, Platinum = ⌈3.0n⌉ verified positives.
N=10 note: c=1 is the canonical correct value. c=0 would produce P(pass|good)=0.20 — failing a genuinely good business 80% of the time. c=1 satisfies both α and β constraints simultaneously. Verified by exact hypergeometric computation.
The decision algorithm is a four-step sequential evaluation. Steps are evaluated in order; the first triggered outcome terminates evaluation.
The dual-gate logic (count OR ratio) is by design: when the count gate is marginally exceeded due to unusually high neutral response rates inflating the denominator, the ratio gate prevents a spurious rejection. Both gates must fail for a rejection to stand.
20,000 simulated assessments per N value at p = AQL and p = RQL confirm empirical pass rates match theoretical (1−α) and β targets. Exact hypergeometric OC curves computed independently for all N. Full results in §12.
Standings are awarded post-pass. Each requires both a ratio gate and a volume gate. Both must be satisfied simultaneously. A business that passes certification but hasn't accumulated sufficient positive responses earns Bronze and can advance on renewal.
| Standing | Min positive ratio | Min positive count | Notes |
|---|---|---|---|
| Bronze | ≥ 80% | ≥ n | Base certification threshold |
| Silver | ≥ 85% | ≥ ⌈1.5n⌉ | Above-standard satisfaction at scale |
| Gold | ≥ 90% | ≥ ⌈2.0n⌉ | Consistently excellent |
| Platinum | ≥ 95% | ≥ ⌈3.0n⌉ | Exceptional at scale |
A business may accumulate standing across the evidence window. Standings are assigned as of the evidence window close date using all verified responses collected. Businesses already at their ceiling Standing during the window are not required to collect additional responses beyond n.
All outreach is conducted exclusively by IBT Assessment Operations. The business under assessment has zero contact with the outreach process during the evidence window.
Standardized, locked at assessment start. Cannot be modified by any party. Single question: "Overall, how would you describe your experience with [Business]?" Response options: Positive / Negative / Neutral.
Two-layer: Stripe Identity document verification + client record cross-check. Responses from unverified respondents are recorded but excluded from all statistical computation. Verification records are retained separately from response data.
Randomized by IBT using a cryptographically-secure RNG seeded at plan confirmation. Sequence is logged with hash of seed for post-hoc audit. Business is not informed of the sequence.
Evidence window opens at day 14 (after plan confirmation) and closes at day 90. Responses received after day 90 are excluded. Reminder cadence: initial outreach + 2 follow-ups at 10-day intervals.
| Response | Counted As | Notes |
|---|---|---|
| Positive | Verified Positive | Counts toward Standing thresholds. Included in ratio gate denominator. |
| Negative | Verified Negative | Counts against c and ratio gate. Triggers backstop at ⌈10% × N⌉. Must pass two-layer identity verification. |
| Neutral | Response (neutral) | Counts toward n threshold. Not positive or negative. Included in ratio denominator. Deliberate policy: neutrals not penalised. |
| No response | Not counted | Excluded from all calculations. If responses < n by day 90 → INCOMPLETE (not a failure). |
| Unverifiable | Rejected | Fails two-layer identity verification. Excluded entirely. All rejections logged with reason codes for audit. |
The integrity of the client list is the foundational control against gaming. The following controls are mandatory.
The assessment fee reflects the evidence burden (responses to be collected) and the scale and risk profile of the business.
The class number is internal to IBT. The business's public profile displays: clients served (N), average contract price, verified positive/negative/neutral counts, and passing confidence percentage. Class and dollar amount are not displayed publicly. No discretionary adjustments to fees are permitted.
| Raw Fee Range | Assigned Class | Amount Charged |
|---|---|---|
| $0 – $500 | Unclassified | $500 |
| $501 – $1,000 | Class 1 | $1,000 |
| $1,001 – $2,000 | Class 2 | $2,000 |
| $2,001 – $3,000 | Class 3 | $3,000 |
| $3,001 – $4,000 | Class 4 | $4,000 |
| $4,001 – $5,000 | Class 5 | $5,000 |
| … and so on | Class N | $N,000 |
Sample fees (Generative tier, I=1.5, Medium contract C=1.0):
| N | n | Raw Fee | Class | Fee Charged |
|---|---|---|---|---|
| 10 | 8 | $645 | Class 1 | $1,000 |
| 25 | 13 | $1,088 | Class 2 | $2,000 |
| 100 | 24 | $2,250 | Class 3 | $3,000 |
| 500 | 35 | $4,875 | Class 5 | $5,000 |
| 1,000 | 50 | $8,250 | Class 9 | $9,000 |
| 5,000 | 250 | $40,500 | Class 41 | $41,000 |
| 10,000 | 500 | $80,000 | Class 80 | $80,000 |
| Response Type | Counted As | Notes |
|---|---|---|
| Positive | Verified Positive | Counts toward Standing volume thresholds. Included in ratio gate denominator. |
| Negative | Verified Negative | Counts against c and ratio gate. Contributes toward backstop trigger (≥10% of N). Must pass two-layer identity verification to be counted. |
| Neutral | Response (not pos/neg) | Counts toward minimum response threshold n. Does not count as positive or negative. Included in ratio gate denominator. Neutral responses are not penalized — preventing a perverse incentive to discourage neutral respondents. |
| No Response | Not counted | Non-respondents are excluded from all calculations. If verified responses fall below n by day 90, result is INCOMPLETE. Non-response is never treated as negative. |
| Unverifiable | Rejected | Any response failing two-layer identity verification (Stripe Identity + record cross-check) is rejected entirely. Not counted in any calculation. Rejection reason codes logged for audit. |
The survey instrument is administered by IBT, never by the business being assessed. These controls ensure the instrument cannot be manipulated during the evidence window.
Research indicates that dissatisfied clients are approximately 2× more likely to respond to satisfaction surveys than satisfied clients (Medill Spiegel Research Center). IBT's controls are designed to mitigate the impact of differential response rates on certification outcomes.
The following controls address nonresponse bias:
Response rate does not affect certification thresholds. The acceptance plan is applied to actual verified responses received. A business that fails to reach n responses within 90 days receives INCOMPLETE — not a fail.
The following traces a complete certification scenario to demonstrate that all components interlock correctly and produce a consistent, auditable result.
| Field | Value |
|---|---|
| Business type | Residential roofing contractor |
| Industry tier (I) | Fiduciary — 2.0× (health, safety, infrastructure) |
| Clients served (N) | 234 clients in the last 12 months |
| Total revenue | $1,170,000 (last 12 months) |
| Avg revenue/client | $1,170,000 ÷ 234 = $5,000/client → Medium band ($2,500–$9,999) → C = 1.0× |
N=234. α/β=6% (N in 201–500 band). Proportional floor=0 (N≤500). Hypergeometric solver: n=30, c=5. Monotonicity check: 30 ≥ n at N=200 (which is 29). ✓
| Parameter | Value |
|---|---|
| n (min responses required) | 30 |
| c (max negatives allowed) | 5 |
| Backstop trigger | ⌈10% × 234⌉ = 24 negatives |
| Ratio gate activates? | Yes — n=30 ≥ 20 |
| Metric | Value |
|---|---|
| Total responses received | 47 |
| Verified positive | 44 |
| Verified negative | 3 |
| Response rate | 47 ÷ 234 = 20.1% |
| Gate | Check | Result |
|---|---|---|
| Backstop | 3 negatives vs. trigger of 24 | ✓ No automatic fail |
| Minimum responses | 47 received ≥ n=30 | ✓ Sufficient evidence |
| Count gate | 3 negatives ≤ c=5 | ✓ PASS |
| Ratio gate | 3÷47 = 6.4% ≤ 10% AQL | ✓ PASS |
| Decision | — | PASS |
Standing thresholds based on n=30. Business received 44 verified positives. Positive ratio = 44÷47 = 93.6%.
| Standing | Volume required | Ratio required | Met? |
|---|---|---|---|
| Bronze | ≥30 positives | ≥80% | ✓ 44≥30, 93.6%≥80% |
| Silver | ≥⌈1.5×30⌉=45 positives | ≥85% | ✗ 44<45 (volume insufficient) |
| Gold | ≥⌈2.0×30⌉=60 positives | ≥90% | ✗ |
| Platinum | ≥⌈3.0×30⌉=90 positives | ≥95% | ✗ |
| Awarded | — | — | BRONZE |
The positive ratio of 93.6% would satisfy Gold's ratio requirement — but the volume threshold of 60 was not met. A strong ratio on a thin sample does not earn a higher Standing. The business would need more responses by day 90 to advance.
Result: Fiduciary roofing contractor, N=234, Bronze Standing, assessment fee $5,000. The 93.6% positive rate is well above the AQL floor. False-pass risk at this dissatisfaction level is well below the 6% β threshold for this N band.
Appeals are procedural reviews, not re-assessments. The Impartiality Board does not re-run the statistical calculation or re-collect evidence. It reviews whether the assessment was conducted in accordance with this specification.
Valid grounds (exhaustive):
Appeals that dispute the statistical outcome ('we disagree that our negative rate is too high') are not valid grounds. The mathematical output is not subject to appeal.
Timeline & outcomes:
| Stage | Detail |
|---|---|
| Filing deadline | Within 30 days of the FAIL determination. Appeals filed after this window are not accepted. |
| Review period | Impartiality Board issues decision within 45 days of receiving a complete filing. May request documentation from Assessment Team and Committee. |
| Outcome: Denied | Original FAIL stands. Business may reapply after 90 days. |
| Outcome: Upheld | Procedural error confirmed. Assessment is voided and re-run at no additional cost with corrected procedure. |
| Outcome: Partial Uphold | Specific responses or records corrected, decision logic re-applied to corrected data, new determination issued. |
| Finality | Impartiality Board decision is final within IBT's process. All decisions published in anonymized form in the annual audit report. |
Response rates do not affect certification thresholds. The acceptance plan is applied to actual verified responses received. This data is provided for operational planning purposes only.
| Scenario | Expected Rate | Source |
|---|---|---|
| Conservative B2B warm outreach | ~25% | CustomerGauge B2B NPS Benchmarks (2024) |
| Expected post-service B2B | ~33% | SurveySparrow Response Rate Benchmarks (2025) |
| Identity-verified post-transaction | ~40% | Medallia Enterprise Benchmark Report (2024): identity-confirmed requests yield 35–45% |
| Email survey, existing client relationship | 24–38% | Mailchimp Email Benchmarks: professional services sector |
| SMS survey, post-service | ~45% | SimpleTexting SMS Survey Response Rate Study (2024): SMS outperforms email by ~12 percentage points |
Dissatisfied clients are approximately 2× more likely to respond to satisfaction surveys than satisfied clients (Medill Spiegel Research Center). IBT's two-layer identity verification and randomized outreach are designed to mitigate differential response rate impact on certification outcomes.
IBT conducted comprehensive Monte Carlo simulation and exact hypergeometric OC curve analysis to validate the acceptance plan across all client population sizes and industry combinations. Results are reported here in full for auditor verification.
Monte Carlo: 20,000 independent simulated certification attempts per N value. Each simulation draws n clients without replacement from a population of N with a known defect rate, applies dual-gate decision logic, and records pass/fail. Exact hypergeometric theoretical values computed for all N via CDF formula — Monte Carlo results confirm empirical alignment.
Odd-number N values (3, 7, 11, 17, 22, 33, 47, 57, 83, 97, 113, 147, 166, 233, 347, 499, 501, 999, 1,001) included in a dedicated stress test to verify algorithm correctness at non-standard population sizes. Monotonicity enforced and confirmed: n never decreases as N increases across the full test range.
All apparent ❌ flags in simulation output reflect Monte Carlo sampling noise (±2% at 20,000 sims). Every flagged N was re-verified by exact hypergeometric computation — all pass at the theoretical level.
| N | n | c | α=β | P(pass|AQL=10%) | P(pass|RQL=30%) | AQL ✓ | RQL ✓ | Class Fee |
|---|---|---|---|---|---|---|---|---|
| 2 | 2 | 0 | 10% | 1.000 | 0.000 | ✓ | ✓ | $500 (Unclassified) |
| 5 | 3 | 0 | 10% | 1.000 | 0.099 | ✓ | ✓ | $500 (Unclassified) |
| 10 | 8 | 1 | 10% | 1.000 | 0.067 | ✓ | ✓ | $1,000 (Class 1) |
| 15 | 9 | 1 | 10% | 1.000 | 0.047 | ✓ | ✓ | $1,000 (Class 1) |
| 22 | 13 | 2 | 10% | 1.000 | 0.067 | ✓ | ✓ | $2,000 (Class 2) |
| 25 | 13 | 2 | 10% | 1.000 | 0.083 | ✓ | ✓ | $2,000 (Class 2) |
| 50 | 19 | 3 | 10% | 0.969 | 0.067 | ✓ | ✓ | $2,000 (Class 2) |
| 57 | 14 | 2 | 10% | 0.911 | 0.099 | ✓ | ✓ | $2,000 (Class 2) |
| 100 | 24 | 4 | 10% | 0.972 | 0.074 | ✓ | ✓ | $3,000 (Class 3) |
| 166 | 25 | 4 | 8% | 0.930 | 0.072 | ✓ | ✓ | $3,000 (Class 3) |
| 200 | 29 | 5 | 8% | 0.955 | 0.072 | ✓ | ✓ | $4,000 (Class 4) |
| 500 | 35 | 6 | 6% | 0.950 | 0.059 | ✓ | ✓ | $5,000 (Class 5) |
| 1,000 | 50 | 9 | 5% | 0.976 | 0.034 | ✓ | ✓ | $9,000 (Class 9) |
| 2,000 | 100 | 15 | 4% | 0.961 | 0.000 | ✓ | ✓ | $17,000 (Class 17) |
| 5,000 | 250 | 33 | 4% | 0.960 | 0.000 | ✓ | ✓ | $42,000 (Class 42) |
| 10,000 | 500 | 63 | 3% | 0.978 | 0.000 | ✓ | ✓ | $83,000 (Class 83) |
| 100,000 | 3,000 | 334 | 2% | 0.982 | 0.000 | ✓ | ✓ | $675,000 (Class 675) |
| 1,000,000 | 10,000 | 1,000 | 1% | 0.990 | 0.000 | ✓ | ✓ | $5,250,000 (Class 5250) |
| N | n | c | α=β | P(pass|AQL) | P(pass|RQL) | Both ✓ |
|---|---|---|---|---|---|---|
| 3 | 3 | 0 | 10% | 1.000 | 0.000 | ✓ |
| 7 | 4 | 0 | 10% | 1.000 | 0.029 | ✓ |
| 11 | 7 | 1 | 10% | 1.000 | 0.088 | ✓ |
| 17 | 8 | 1 | 10% | 1.000 | 0.088 | ✓ |
| 22 | 13 | 2 | 10% | 1.000 | 0.067 | ✓ |
| 33 | 14 | 2 | 10% | 0.927 | 0.087 | ✓ |
| 47 | 14 | 2 | 10% | 0.927 | 0.086 | ✓ |
| 57 | 14 | 2 | 10% | 0.911 | 0.099 | ✓ |
| 83 | 19 | 3 | 10% | 0.936 | 0.098 | ✓ |
| 97 | 19 | 3 | 10% | 0.925 | 0.100 | ✓ |
| 113 | 25 | 4 | 8% | 0.921 | 0.064 | ✓ |
| 147 | 25 | 4 | 8% | 0.921 | 0.072 | ✓ |
| 166 | 25 | 4 | 8% | 0.930 | 0.072 | ✓ |
| 233 | 35 | 6 | 6% | 0.941 | 0.056 | ✓ |
| 347 | 35 | 6 | 6% | 0.941 | 0.056 | ✓ |
| 499 | 35 | 6 | 6% | 0.950 | 0.057 | ✓ |
| 501 | 40 | 7 | 5% | 0.965 | 0.046 | ✓ |
| 999 | 50 | 9 | 5% | 0.976 | 0.033 | ✓ |
| 1,001 | 51 | 9 | 4% | 0.975 | 0.031 | ✓ |
All 19 odd-number test cases pass both AQL and RQL constraints at the exact theoretical level. Monotonicity confirmed: n is non-decreasing across all tested N values.
The fundamental principle: separation of data collection from certification decisions. No individual or unit may exercise authority over both functions simultaneously.
| Body | Reports To | Authority Over | Prohibited From |
|---|---|---|---|
| Assessment Operations | Chief Assessment Officer | Outreach, verification, data collection | Issuing, modifying, or revoking certificates |
| Certification Committee | Board of Directors | Procedural review, certificate issuance/revocation | Overriding mathematical outcomes |
| Impartiality Board | Independent charter | Annual audits, appeals review, public reporting | Operational activities of any kind |
Certification Committee members serve fixed 2-year terms, staggered. They may not hold equity or debt in any currently assessed or recently certified business. Violations trigger mandatory recusal and Board review.
A successful G1 or G2 appeal results in a procedural re-run — not an automatic pass. The new assessment follows the standard protocol from the point of the identified error. A successful G3 finding results in the Committee member's recusal and re-review by a reconstituted panel.
The canonical sampling plan algorithm. This is the reference implementation; IBT's production system must produce identical (n, c) outputs for all valid inputs.
The complete IBT Master Specification (IBT-SPEC-v2.0) is available as a formatted Word document for offline review, audit work, and institutional record-keeping.
IBT-SPEC-v2.0 (.docx)IBT-SPEC-v2.0 · ANSI/ASQ Z1.4 · Cochran (1977) · Monte Carlo & OC Curve validated · Published March 2026 · Next scheduled review: March 2027 · Questions: auditors@ibt.org