Pollution Cost Population Share Tool

Description

Sum population*perPersonCost into totalCost, and into includedCost only where included is true.

Average, incremental and marginal environmental costs answer different questions. A ratio over a finite reduction is a step average, while marginal cost describes an additional unit; meaningful comparisons need common periods, boundaries and units.

Sum population*perPersonCost into totalCost, and into includedCost only where included is true.

When to use this tool

Use Pollution Cost Population Share when checking a supplied environmental cost contribution or comparison.

How to use the tool and how it works

Enter populations, perPersonCosts, included. Keep parallel arrays aligned. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read totalCost, includedCost, includedShare, defined. Inspect defined before interpreting the associated values.

Require equally long populations, perPersonCosts and included arrays and nonnegative populations and costs. Sum population*perPersonCost into totalCost, and into includedCost only where included is true. Return includedShare = includedCost/totalCost when positive, otherwise includedShare = 0 and defined = false.^[1]

Input field	Meaning and units	Accepted input
populations	Populations	Required. Array of finite number; maximum items 256.
perPersonCosts	Per Person Costs	Required. Array of finite number; maximum items 256.
included	Included	Required. Array of boolean; maximum items 256.

Output field	Interpretation	Returned shape
totalCost	Total Cost	Required. Finite number.
includedCost	Included Cost	Required. Finite number.
includedShare	Included Share	Required. Finite number.
defined	Whether the denominator is positive and the returned ratio is defined; inspect this before using a zero placeholder.	Required. Boolean.

json

{
  "input": {
    "populations": [
      10,
      20
    ],
    "perPersonCosts": [
      2,
      3
    ],
    "included": [
      true,
      false
    ]
  },
  "output": {
    "totalCost": 80,
    "includedCost": 20,
    "includedShare": 0.25,
    "defined": true
  }
}

Limitations and assumptions

This is a cost-weighted share, not a population share or estimate of causal environmental harm. Population weights may be fractional under the contract, records are not deduplicated, and zero total cost makes the share undefined.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Assemble comparable costs and effects across the full baseline and project, and distinguish financial costs from social costs before ranking alternatives.

References

Calculation and input contract: environmental-economics/pollution-cost-population-share — tool.io

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