{
  "document_type": "aggregate_product_data_snapshot",
  "title": "English AIdol IELTS Writing practice aggregate snapshot",
  "owner": "English AIdol",
  "extracted_at": "2026-07-11T00:45:36Z",
  "observation_window": {
    "first_submission_at": "2025-08-22T04:54:17.514234Z",
    "last_submission_at": "2026-07-10T07:19:47.848021Z"
  },
  "inclusion_rule": "Rows in writing_test_results joined to test_results where test_type was writing or IELTS Writing and band_scores was not null at extraction time.",
  "aggregate_counts": {
    "scored_submissions": 617,
    "distinct_accounts": 69,
    "task_1_submissions": 302,
    "task_2_submissions": 315,
    "rows_with_all_four_comparable_criteria": 528,
    "criterion_average_denominator": 528,
    "rows_with_recorded_word_count": 617,
    "rows_with_recorded_time_taken_seconds": 0
  },
  "aggregate_values": {
    "average_word_count": 237.49,
    "average_internal_four_criterion_mean_on_complete_rows": 6.48,
    "average_task_achievement_or_response_estimate": 6.54,
    "average_coherence_and_cohesion_estimate": 6.66,
    "average_lexical_resource_estimate": 6.29,
    "average_grammatical_range_and_accuracy_estimate": 6.43
  },
  "complete_row_internal_half_step_distribution": {
    "1.0": 6,
    "2.5": 1,
    "3.5": 6,
    "4.0": 11,
    "4.5": 15,
    "5.0": 43,
    "5.5": 49,
    "6.0": 84,
    "6.5": 68,
    "7.0": 55,
    "7.5": 95,
    "8.0": 63,
    "8.5": 17,
    "9.0": 15
  },
  "privacy_and_method_notes": [
    "Only aggregate counts and averages are published; no submission text, feedback text, account identifier, or individual result is included.",
    "The sample is self-selected product activity and includes repeat attempts, so it is not representative of IELTS candidates or English learners generally.",
    "The values are outputs from English AIdol models used at different times and were not validated against examiner-awarded IELTS scores.",
    "The internal four-criterion mean is an analytical summary of stored model outputs, not an official IELTS band or a prediction.",
    "No timing result is reported because the selected IELTS rows had no recorded time_taken_seconds values.",
    "This snapshot cannot support causal claims, score-improvement claims, examiner agreement, accuracy percentages, or anonymized example publication."
  ],
  "metric_definitions": {
    "comparable_criteria_row": "A selected row where task_achievement or task_response, coherence_and_cohesion, lexical_resource, and grammatical_range_and_accuracy were all stored as objects containing a numeric band value.",
    "criterion_averages": "Calculated across the 528 comparable-criteria rows only.",
    "average_word_count": "Calculated across all 617 selected rows; every selected row had a recorded word_count value.",
    "half_step_distribution": "The arithmetic mean of the four stored band values on each comparable-criteria row, grouped to the nearest 0.5 for an internal descriptive distribution."
  },
  "refresh_policy": "Create a new dated immutable snapshot after rerunning the documented aggregate query; do not silently replace this historical snapshot."
}