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Enum: Null Semantics (NullSemanticsEnum)

The kind of "missing or zero" a per-value cell carries. A blank or a 0 is ambiguous: structural_null, derived_null and true_zero have opposite correct handling (drop / drop-from-denominator / keep-as-zero), and conflating them biases the health-effect estimate — nulls should be excluded from percentile-ranking denominators for exactly this reason.

URI: envar:enum/NullSemanticsEnum

Permissible Values

Value Meaning Description
present None A real, non-missing value
structural_null None No source data for this cell — the cell lies outside the source product's cov...
derived_null None Aggregation was impossible — geometry mismatch, no overlap between source and...
true_zero None A real, measured absence of the exposure or event

Identifier and Mapping Information

Schema Source

LinkML Source

name: NullSemanticsEnum
description: 'The kind of "missing or zero" a per-value cell carries. A blank or a
  `0` is ambiguous: `structural_null`, `derived_null` and `true_zero` have opposite
  correct handling (drop / drop-from-denominator / keep-as-zero), and conflating them
  biases the health-effect estimate — nulls should be excluded from percentile-ranking
  denominators for exactly this reason.'
title: Null Semantics
from_schema: https://w3id.org/linkml/microschemas/envar
rank: 1000
permissible_values:
  present:
    text: present
    description: A real, non-missing value.
  structural_null:
    text: structural_null
    description: No source data for this cell — the cell lies outside the source product's
      coverage. Drop; do not impute from neighbours.
  derived_null:
    text: derived_null
    description: Aggregation was impossible — geometry mismatch, no overlap between
      source and target support. Drop from denominators; flag the geometry mismatch.
  true_zero:
    text: true_zero
    description: A real, measured absence of the exposure or event. Keep as zero.