{
  "schema": "vedokrok.public-item.v1",
  "release_id": "MHC-RPUB-20260920-75ad787a",
  "url": "/knowledge/ask-what-was-randomized",
  "id": "MHC-D-RESEARCH-0261",
  "version": "0.1.0",
  "title": "Ask what was randomized",
  "summary": "A random draw into a group and a random allocation inside it solve different problems.",
  "kind": "concept",
  "body": "Separate selection from assignment. Selection concerns who enters the study; assignment concerns which condition participating units receive. Random assignment supports causal comparison when implemented and analyzed appropriately, but it does not automatically make a volunteer sample representative of everyone.",
  "limits": [
    "Randomization balances other influences in expectation, not perfectly in every small sample."
  ],
  "topics": [
    "union-statistical-judgment"
  ],
  "intents": [],
  "source_ids": [
    "RS-26F1D4FD9F13C1E9"
  ],
  "evidence": [
    {
      "claim": "Random assignment allocates participating units to conditions; it is distinct from randomly selecting units from a population.",
      "source_id": "RS-26F1D4FD9F13C1E9",
      "role": "supports",
      "note": "Assignment balances differences in expectation, not perfectly in every realized sample, and does not establish population representativeness.",
      "locator": "Random assignment and experimental units"
    }
  ],
  "use_when": [
    "A study calls itself randomized and the word is doing most of the persuasion."
  ],
  "avoid_when": [
    "Randomization balances other influences in expectation, not perfectly in every small sample."
  ],
  "example": "Volunteers allocated randomly between two training formats remain volunteers, even when the comparison between formats is well designed.",
  "check": "You can name the randomization step and the claim it supports.",
  "sources": [
    {
      "id": "RS-26F1D4FD9F13C1E9",
      "title": "Introductory Statistics 2e, 1.4: Experimental Design and Ethics",
      "url": "https://openstax.org/books/introductory-statistics-2e/pages/1-4-experimental-design-and-ethics"
    }
  ],
  "relations": [
    {
      "from": "MHC-D-RESEARCH-0261",
      "to": "MHC-D-RESEARCH-0262",
      "type": "useful_with",
      "url": "/knowledge/hide-condition-labels-from-the-person-judging-the-outcome"
    }
  ],
  "collections": [
    {
      "id": "RC-D4FD0B28897E9517",
      "title": "Check what a study can actually tell you",
      "url": "/collections/check-what-a-study-can-actually-tell-you"
    }
  ]
}