Source: https://guthlabs.ai/docs/instruments/purchasing-power-parity-ppp-comparator/

instrument / verified-clean

# Purchasing Power Parity (PPP) Comparator

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/purchasing-power-parity-ppp-comparator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/purchasing-power-parity-ppp-comparator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/purchasing-power-parity-ppp-comparator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/purchasing-power-parity-ppp-comparator/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Finance, Economics & Business (educational only — never individualized investment, tax, or legal advice)

**Tranche**: tranche-7

**Evidence ID**: t7-097

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The core arithmetic is standard under the stated local-currency-per-international-dollar convention. The instrument cannot receive an unconditional PASS until the required World Bank series and year are made explicit inputs or fixed configuration, and the comparison-note behavior is defined. The two United States vectors use the exact widely memorized international-dollar reference entry of 1.000.

### Formula and scope findings

- The ratio formula is conditionally correct only when both PPP conversion factors use the same year, PPP concept, and unit convention of local-currency units per international dollar: target_amount = base_amount × target_factor ÷ base_factor.

- The specification does not identify which World Bank PPP series is required, such as GDP PPP versus private-consumption PPP; these are different datasets and can produce different results.

- The year is not an input, although PPP factors are year-dated and must be compared within the same year.

- The output 'comparison note' has no defined algorithm or required content.

- The formula assumes amount is denominated in the base country's local currency and produces an amount in the target country's local currency at PPP; this is not a market-exchange-rate conversion.

### Unit assumptions

- PPP conversion factors are local currency units per international dollar.

- Both factors use the World Bank ICP 2021 GDP PPP series, indicator PA.NUS.PPP, and values are treated as the displayed table values.

- The input amount is in the base country's local currency; the output PPP-adjusted amount is in the target country's local currency.

- The comparison is a cost-level comparison, not an individualized investment, tax, legal, or purchasing recommendation.

- Country names identify the currencies used: USD for the United States, INR for India, and CNY for China.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The specification provides no explicit validation behavior for a zero base PPP factor, yet the formula becomes undefined through division by zero. It also leaves amount denomination, sign handling, and country-direction conventions implicit. The formula-branch probe finds no legitimate branch in the stated model; an implementation must not invent one at the factor-ratio parity point.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "amount": 100,
    "base_country": "United States",
    "target_country": "India",
    "year": 2021,
    "ppp_series": "GDP PPP",
    "amount_currency": "USD"
  },
  "expected_outputs": {
    "ppp_adjusted_amount": 2256.5,
    "output_currency": "INR",
    "comparison_note": "At 2021 GDP-PPP price levels, USD 100 in the United States corresponds to approximately INR 2,256.50 in India; this is not a market exchange-rate quote."
  },
  "reference_data": {
    "base_country": "United States",
    "base_ppp_conversion_factor_lcu_per_international_dollar": 1,
    "target_country": "India",
    "target_ppp_conversion_factor_lcu_per_international_dollar": 22.565,
    "source_convention": "World Bank ICP 2021 GDP PPP, indicator PA.NUS.PPP; displayed World Bank table values; United States factor 1.000 is the standard international-dollar reference entry."
  },
  "working": "PPP-adjusted amount = amount × (target factor ÷ base factor) = 100 USD × (22.565 INR/international dollar ÷ 1.000 USD/international dollar) = 100 × 22.565 = 2,256.5 INR."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`