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DHS GE/GPS Geography

Product status: REPORTED-COORDINATE CLUSTER GEOGRAPHY IMPLEMENTED
Authority: SOURCE-NATIVE CLUSTER SILVER + AUDITABLE GEOGRAPHY RELATION
Real protected-data acceptance: NOT RECORDED IN THIS SITE
Experiment-use status: NOT YET A CURRENT DHS EXPERIMENT INPUT
Producing repository: fcv-empirical-data

What it is​

The DHS GE/GPS vertical preserves public DHS cluster coordinates as reported spatial measurements with explicit displacement uncertainty.

external DHS GE/GPS file
        ↓
SourceSnapshotRef
        ↓
source-native cluster Silver
        ↓
survey / GPS identity audit
        ↓
reported-coordinate spatial membership
        ↓
SurveyGeographyLink + uncertainty metadata

The key phrase is reported-coordinate. This product never claims that a public DHS point is the cluster's exact true location.

Natural grain​

Cluster Silver preserves one supplied GPS row as one row, with a technical row identity so duplicates remain observable.

The normalized envelope preserves, where supplied/documented:

  • survey identity;
  • cluster identity / DHSID;
  • reported latitude and longitude;
  • source-defined urban/rural classification;
  • source release and snapshot identity;
  • coordinate validity;
  • whether the coordinate is displaced;
  • release-specific displacement-policy metadata;
  • every source-native field.

If the source is geospatial, source geometry is retained as source information rather than reinterpreted as an undisplaced true location.

Displacement semantics​

Displacement metadata is release-specific provenance, not a hardcoded universal DHS rule table.

The caller may attach only documentation-supported policy facts such as urban/rural displacement limits, exceptional rural displacement policy, or policy source. The implementation deliberately has no universal default displacement radius.

It does not perform:

  • de-displacement;
  • true-location inference;
  • nearest-project snapping;
  • displacement-buffer matching as if exact;
  • silent coordinate repair.

A coordinate placeholder is treated as such only when the release-specific convention is explicitly supplied.

Survey / GPS identity audit​

The GPS vertical does not silently inner-join clusters and discard discrepancies.

The linkage audit can preserve:

  • survey-only clusters;
  • GPS-only clusters;
  • duplicate cluster rows;
  • conflicting survey identity;
  • source survey-ID conflicts.

This matters because an experiment should not acquire apparently clean geography by losing difficult clusters during linkage.

Reported-coordinate geography membership​

Only valid reported points are sent to spatial-data-foundation for polygon membership.

The resulting relation is explicitly named:

reported_coordinate_membership

It preserves shared geography identity and membership status. Exact-boundary or overlapping-polygon cases may remain ambiguous_multiple; outside points remain outside; unusable coordinates remain invalid rather than being assigned by convenience.

The relation carries displacement and uncertainty metadata alongside the geography result.

What the membership means​

A matched row means:

the coordinate supplied in the public DHS GPS file falls inside this analytical polygon.

It does not mean:

the undisplaced household/cluster location is definitely in this polygon.

That distinction is scientifically important near administrative boundaries, around small spatial exposures, and whenever an experiment uses nearest-project or radius-based treatment definitions.

Future uncertainty-aware geography​

The implementation reserves a separate semantic concept:

possible_geography_under_displacement

for a future product that could enumerate geography candidates consistent with an authoritative displacement policy.

That future product would complement reported-coordinate membership. It would not overwrite the reported coordinate or manufacture a single true location.

The candidate/buffer product is not yet implemented.

Relationship to HR and GC​

GPS geography is a cluster-level product. It does not contain HR household variables or GC covariates.

A scientific DHS design may later combine:

HR household → verified cluster identity
GC cluster covariates → same verified cluster identity
GPS cluster geography → reported-coordinate relation

but that composition must preserve the different grains and displacement uncertainty.

Known limitations / do not infer​

Do not infer that:

  • geo_uid from reported-coordinate membership is the true undisplaced cluster geography;
  • a unique reported-point match eliminates displacement uncertainty;
  • a GPS-only missing cluster can be silently removed from HR;
  • two clusters in the same ADM are the same cluster;
  • public coordinates support exact nearest-project exposure without sensitivity analysis;
  • geography membership assigns treatment or outcome meaning.

Experiment history​

No current DHS experiment has yet consumed this geography relation in the forward-looking harness.

The next scientific-use layer should explicitly state how displacement uncertainty affects exposure assignment and should distinguish reported-point sensitivity from any future uncertainty-aware candidate geography.

Technical reference​