{
  "report_id": "138-class-arrival-timing",
  "version": "1.0",
  "status": "validated",
  "period": {"start": "2025-01-01", "end_exclusive": "2026-01-01"},
  "sample": {"tenants_attempted": 2174, "tenants_succeeded": 2174, "tenants_failed": 0, "centers_with_any_access_read": 222, "eligible_centers": 173, "eligible_reads": 1987788, "total_reads": 2940128},
  "primary": {"window_minutes": [-60, 30], "minimum_reads_per_center": 100, "median_of_center_medians_min": 1.00, "p25_center_median_min": -3.00, "p75_center_median_min": 3.00, "median_center_at_or_after_start_pct": 63.75, "mean_center_at_or_after_start_pct": 58.40, "median_center_more_than_5_min_late_pct": 22.21, "raw_at_or_after_start_pct": 55.05},
  "distribution": [
    {"band": "15 o más min antes", "median_center_pct": 1.91, "raw_pct": 10.36},
    {"band": "5–14 min antes", "median_center_pct": 10.43, "raw_pct": 17.88},
    {"band": "Últimos 4 min", "median_center_pct": 15.88, "raw_pct": 16.71},
    {"band": "Inicio a 5 min después", "median_center_pct": 27.78, "raw_pct": 28.40},
    {"band": "6–15 min después", "median_center_pct": 13.73, "raw_pct": 15.45},
    {"band": "16–30 min después", "median_center_pct": 8.10, "raw_pct": 11.20}
  ],
  "sensitivity": [
    {"window_minutes": [-120, 60], "centers": 173, "reads": 2336147, "median_of_center_medians_min": 2.00, "median_center_at_or_after_start_pct": 68.61},
    {"window_minutes": [-60, 30], "centers": 173, "reads": 1987788, "median_of_center_medians_min": 1.00, "median_center_at_or_after_start_pct": 63.75},
    {"window_minutes": [-30, 30], "centers": 172, "reads": 1932069, "median_of_center_medians_min": 1.00, "median_center_at_or_after_start_pct": 63.92}
  ],
  "daypart_comparison": {
    "article_id": "139-access-timing-dayparts",
    "window_minutes": [-30, 30],
    "morning_definition": "class start before 12:00",
    "evening_definition": "class start at or after 17:00",
    "minimum_reads_per_daypart": 100,
    "paired_centers": 153,
    "morning_reads": 660273,
    "evening_reads": 969553,
    "median_morning_from_start_pct": 68.04,
    "median_evening_from_start_pct": 60.64,
    "median_within_center_difference_pp": -4.62,
    "p25_difference_pp": -12.33,
    "p75_difference_pp": 2.83,
    "centers_evening_lower": 99,
    "centers_evening_lower_pct": 64.71,
    "largest_center_combined_share_pct": 3.63,
    "sensitivity": [
      {"minimum_reads_per_daypart": 50, "paired_centers": 161, "median_within_center_difference_pp": -4.64, "centers_evening_lower_pct": 65.22},
      {"minimum_reads_per_daypart": 100, "paired_centers": 153, "median_within_center_difference_pp": -4.62, "centers_evening_lower_pct": 64.71},
      {"minimum_reads_per_daypart": 500, "paired_centers": 125, "median_within_center_difference_pp": -4.30, "centers_evening_lower_pct": 63.20}
    ]
  },
  "quality": {"largest_center_read_share_pct": 4.19, "broad_window_share_of_all_reads_pct": 79.47, "center_reconciliations_passed": true, "center_balanced_primary": true},
  "scope": {"access_read_not_proven_physical_arrival": true, "class_start_and_read_in_local_time": true, "centers_without_access_system_out_of_scope": true},
  "privacy": {"member_identifiers_exported": false, "exact_timestamps_exported": false, "center_identifiers_exported": false}
}