Source: https://guthlabs.ai/docs/instruments/salary-raise-purchasing-power-check/implementation/

instrument implementation / implementation-contract

# Salary/Raise Purchasing-Power Check implementation

A source-bound implementation contract for Salary/Raise Purchasing-Power Check; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-027

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero old_salary produces an undefined division, so the instrument requires explicit input validation and rejection. The specification does not state such validation behavior.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "old_salary": 20000,
    "new_salary": 100000,
    "old_period": "CPI-U base period 1982-84",
    "new_period": "2023 annual average"
  },
  "expected_outputs": {
    "real_change": 0.640948,
    "real_percent_change": 64.0948,
    "plain_language_verdict": "The raise exceeded inflation; purchasing power increased."
  },
  "reference_data": {
    "cpi_old": {
      "period": "1982-84",
      "cpi_u_index": 100,
      "source_convention": "widely tabulated standard value; BLS CPI-U index base convention, U.S. city average, all items, not seasonally adjusted"
    },
    "cpi_new": {
      "period": "2023 annual average",
      "cpi_u_index": 304.702,
      "source_convention": "widely tabulated standard value; BLS CPI-U annual average, U.S. city average, all items, not seasonally adjusted, 1982-84=100"
    }
  },
  "working": "Salary ratio = 100000 / 20000 = 5. CPI ratio = 304.702 / 100.000 = 3.04702. Real change = 5 / 3.04702 - 1 = 1.6409475 - 1 = 0.6409475, which rounds to 0.640948. Real percent change = 0.6409475 x 100 = 64.09475%, or 64.0948%. The old CPI is exactly the famous 1982-84 CPI index-base entry of 100."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/salary-raise-purchasing-power-check/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/salary-raise-purchasing-power-check/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/salary-raise-purchasing-power-check/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

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