{
  "$schema": "https://terraevidence.com/evidence-record.schema.json",
  "recordId": "EP-PUB-005",
  "version": "1.0",
  "status": {
    "code": "reviewed-for-stated-scope",
    "label": "Reviewed for stated scope",
    "meaning": "Checked for the stated wording, sources, methods, context, limits, and review period; not universally proven."
  },
  "topic": "Causal reasoning",
  "title": "A change after treatment is not proof of causation.",
  "claim": "One unreplicated before-and-after observation does not by itself establish that a treatment caused the observed change.",
  "summary": "A change observed after a soil amendment, product, or practice may be real, but timing alone cannot separate the treatment effect from weather, field variation, measurement variation, other management, or chance. A causal claim needs an appropriate comparison and a design capable of testing alternative explanations.",
  "evidenceSupports": [
    "Define the treatment and outcome before testing. Use an appropriate control or comparison, real independent replication, random assignment where feasible, consistent measurement, and a design that accounts for known field variation. Preserve null results, uncertainty, departures from the design, and limits on where the result may apply."
  ],
  "doesNotEstablish": [
    "Sequence alone does not establish causation. One treated plot, one before-and-after comparison, repeated measurements from the same experimental unit, or an uncontrolled demonstration cannot by itself separate a treatment effect from natural variability, co-occurring changes, measurement error, or chance."
  ],
  "sources": [
    {
      "sourceId": "EP-PUB-005-S1",
      "sourceType": "institutional-guidance",
      "institution": "University of Minnesota Extension",
      "title": "How to do research on your farm",
      "url": "https://extension.umn.edu/farm-research/how-do-research-your-farm",
      "relevance": "Explains the need for control treatments, independent replication, randomization, attention to field variability, and restraint against extrapolating one experiment to other fields."
    },
    {
      "sourceId": "EP-PUB-005-S2",
      "sourceType": "institutional-guidance",
      "institution": "Sustainable Agriculture Research and Education",
      "title": "Basics of Experimental Design",
      "url": "https://www.sare.org/publications/how-to-conduct-research-on-your-farm-or-ranch/Basics-of-Experimental-Design/",
      "relevance": "Describes how replication, blocking, and randomization reduce experimental error and help separate treatment effects from natural field variability."
    },
    {
      "sourceId": "EP-PUB-005-S3",
      "sourceType": "institutional-guidance",
      "institution": "National Institute of Standards and Technology",
      "title": "Completely randomized designs",
      "url": "https://www.itl.nist.gov/div898/handbook/pri/section3/pri331.htm",
      "relevance": "Documents randomized assignment, replication, balance, and response comparison as defining elements of a completely randomized experiment."
    }
  ],
  "scope": {
    "reviewedPeriod": "2026-08",
    "applicability": [
      "Evaluating causal claims about soil amendments, products, practices, or management changes when the available evidence is a field observation, demonstration, or before-and-after comparison."
    ],
    "limitations": [
      "Does not require every useful observation to be a randomized experiment; it limits what can be concluded from an observation that lacks a design capable of testing causation.",
      "Does not determine whether a particular treatment works and does not provide personalized fertilizer, lime, amendment, crop, environmental, pest-control, or safety recommendations."
    ],
    "openQuestion": "Which practical small-scale garden designs provide the strongest causal information while remaining affordable and usable for first-time experimenters?"
  },
  "useBoundary": "This reviewed record supports cautious causal reasoning and practical experimental design. It does not determine that a particular treatment caused a change, endorse a product or practice, or provide personalized fertilizer, lime, amendment, crop, environmental, pest-control, or safety recommendations. Treat uncontrolled observations as observations, preserve alternative explanations, and seek appropriate technical guidance when a consequential decision requires stronger evidence.",
  "humanReadableUrl": "https://terraevidence.com/earth-project-reviewed-foundations#ep-pub-005",
  "machineReadableUrl": "https://terraevidence.com/evidence-records/ep-pub-005.json",
  "revision": {
    "version": "1.0",
    "publishedDate": "2026-08-17",
    "lastReviewedPeriod": "2026-08"
  }
}