Create test cohort

POST /api/v2/buyer/advertisers/{advertiserId}/test-cohorts Creates a test cohort — a flexible audience definition (geo, segment, zip code, or custom) that fills one arm of an incrementality test. Incrementality tests compare a TREATMENT cohort against a matched CONTROL.

Request

curl -X POST https://api.interchange.io/api/v2/buyer/advertisers/12345/test-cohorts \
  -H "Authorization: Bearer $SCOPE3_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "West Coast Treatment Group",
    "description": "Users in CA, OR, WA receiving full ad exposure",
    "cohortType": "geographic",
    "role": "TREATMENT",
    "definition": {
      "type": "geo_region",
      "regions": ["US-CA", "US-OR", "US-WA"]
    },
    "estimatedSize": 50000
  }'

{
  "name": "Mountain West Control",
  "cohortType": "geographic",
  "role": "CONTROL",
  "definition": {
    "type": "geo_region",
    "regions": ["US-AZ", "US-NV", "US-NM"]
  },
  "estimatedSize": 48000
}

Parameters

Field	Type	Required	Notes
`advertiserId`	string	Yes	Path parameter — the owning advertiser
`name`	string	Yes	Cohort label (max 255)
`cohortType`	string	Yes	Free-form classification (e.g. `geographic`, `demographic`, `behavioral`)
`definition`	object	Yes	Targeting definition. `type` is required (`zip_code`, `user_segment`, `geo_region`, `custom`); additional fields vary by type
`description`	string	No	Free-text description (max 1000)
`role`	enum	No	`TREATMENT`, `CONTROL`, `OBSERVATION` (default `TREATMENT`)
`estimatedSize`	integer	No	Size estimate for power analysis

Response

{
  "id": "42",
  "advertiserId": "12345",
  "name": "West Coast Treatment Group",
  "description": "Users in CA, OR, WA receiving full ad exposure",
  "cohortType": "geographic",
  "role": "TREATMENT",
  "definition": { "type": "geo_region", "regions": ["US-CA", "US-OR", "US-WA"] },
  "estimatedSize": 50000,
  "isActive": true,
  "createdAt": "2026-01-15T10:30:00Z",
  "updatedAt": "2026-01-15T10:30:00Z"
}

The returned id is the cohortId you pass to Get, Update, and Delete.

Errors

400 VALIDATION_ERROR — missing name, cohortType, or definition.type, or invalid role.
404 NOT_FOUND — advertiserId does not exist or is not visible to the authenticated account.

See Errors for the full error contract.

Measurement tasks

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Measurement overview

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List test cohorts

See defined cohorts

Create measurement source Delete test cohort

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Request

Parameters

Response

Errors

Measurement tasks

Measurement overview

List test cohorts

​Request

​Parameters

​Response

​Errors

​Related

Measurement tasks

Measurement overview

List test cohorts

Request

Parameters

Response

Errors

Related