[
  {
    "name": "country",
    "description": "Country or countries where the study population was recruited or data originates. Use standard country names.",
    "data_type_primary": "array-string",
    "examples": [
      "United Kingdom",
      "United States",
      "Denmark",
      "International"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "study_size",
    "description": "Total number of participants in the analysed cohort as a numeric value if explicitly stated; null if absent.",
    "data_type_primary": "number",
    "examples": [
      "32091",
      "1263"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "year_coverage",
    "description": "Decade bins covering the study data collection period. Select all applicable ranges.",
    "data_type_primary": "array-string",
    "examples": [
      "1980-1989",
      "1990-1999",
      "2000-2009",
      "2010-2019",
      "2020-2029"
    ],
    "examples_mode": "enum",
    "depth": "minimal"
  },
  {
    "name": "gender",
    "description": "Sex distribution of the study population.",
    "data_type_primary": "string",
    "examples": [
      "Both",
      "Male",
      "Female",
      "Not Applicable"
    ],
    "examples_mode": "enum",
    "depth": "minimal"
  },
  {
    "name": "age",
    "description": "Age categories of the study population. Select all applicable bins based on stated age range or mean/median age.",
    "data_type_primary": "array-string",
    "examples": [
      "<45",
      "45-65",
      "65+"
    ],
    "examples_mode": "enum",
    "depth": "minimal"
  },
  {
    "name": "publication_type",
    "description": "Study design or publication type explicitly stated.",
    "data_type_primary": "string",
    "examples": [
      "Prospective cohort study",
      "Retrospective cohort study",
      "Meta-analysis",
      "Randomized controlled trial",
      "Cross-sectional study",
      "Systematic review"
    ],
    "examples_mode": "enum",
    "depth": "minimal"
  },
  {
    "name": "model_type",
    "description": "Statistical or analytical modelling approaches used.",
    "data_type_primary": "array-string",
    "examples": [
      "Cox proportional hazards model",
      "Logistic regression",
      "Random-effect meta-analysis",
      "Poisson regression"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "data_source",
    "description": "Dataset, registry, cohort, or database from which study data were obtained.",
    "data_type_primary": "array-string",
    "examples": [
      "UK Biobank",
      "NHANES",
      "Clinical Practice Research Datalink"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "subpopulation",
    "description": "Specific subgroups or eligibility criteria analysed within the study.",
    "data_type_primary": "array-string",
    "examples": [
      "General population",
      "Smokers",
      "COPD",
      "Lung Cancer",
      "Hypertensive subjects"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "age_exact",
    "description": "Exact reported age summary statistic when available (e.g. mean, median with SD/IQR); null if absent.",
    "data_type_primary": "string",
    "examples": [
      "59.7 (11.9)",
      "~55",
      "68.9 (12.8)"
    ],
    "examples_mode": "guide",
    "depth": "minimal"
  },
  {
    "name": "follow_up_years",
    "description": "Duration of participant follow-up in predefined year ranges. Select all applicable bins.",
    "data_type_primary": "array-string",
    "examples": [
      "<5",
      "5-9",
      "10-19",
      "20+"
    ],
    "examples_mode": "enum",
    "depth": "minimal"
  }
]