{
    "classifications": [
        {
            "column": "user_id",
            "role": "identifier",
            "confidence": 0.98,
            "reason": "Unique per row key (USR-xxxxx)"
        },
        {
            "column": "age",
            "role": "measure",
            "confidence": 0.6,
            "reason": "Numeric age 18-65, 48 distinct values; commonly averaged, though could be banded for grouping"
        },
        {
            "column": "gender",
            "role": "dimension",
            "confidence": 0.98,
            "reason": "Low-cardinality categorical"
        },
        {
            "column": "occupation_type",
            "role": "dimension",
            "confidence": 0.98,
            "reason": "Low-cardinality category"
        },
        {
            "column": "chronotype",
            "role": "dimension",
            "confidence": 0.98,
            "reason": "Low-cardinality category"
        },
        {
            "column": "bedtime_phone_minutes",
            "role": "measure",
            "confidence": 0.9,
            "reason": "Numeric duration in minutes, aggregated"
        },
        {
            "column": "primary_bedtime_app",
            "role": "dimension",
            "confidence": 0.97,
            "reason": "Low-cardinality category"
        },
        {
            "column": "screen_brightness_pct",
            "role": "measure",
            "confidence": 0.88,
            "reason": "Numeric percentage, averaged"
        },
        {
            "column": "blue_light_filter_active",
            "role": "dimension",
            "confidence": 0.97,
            "reason": "Boolean flag 0/1"
        },
        {
            "column": "caffeine_post_5pm_mg",
            "role": "measure",
            "confidence": 0.93,
            "reason": "Quantity in mg, aggregated"
        },
        {
            "column": "physical_activity_min",
            "role": "measure",
            "confidence": 0.93,
            "reason": "Duration in minutes, aggregated"
        },
        {
            "column": "sleep_latency_min",
            "role": "measure",
            "confidence": 0.95,
            "reason": "Continuous duration in minutes"
        },
        {
            "column": "total_sleep_hours",
            "role": "measure",
            "confidence": 0.96,
            "reason": "Continuous hours, averaged"
        },
        {
            "column": "deep_sleep_pct",
            "role": "measure",
            "confidence": 0.95,
            "reason": "Continuous percentage metric"
        },
        {
            "column": "rem_sleep_pct",
            "role": "measure",
            "confidence": 0.95,
            "reason": "Continuous percentage metric"
        },
        {
            "column": "morning_alarm_snoozes",
            "role": "measure",
            "confidence": 0.85,
            "reason": "Count of snoozes, aggregated"
        },
        {
            "column": "next_day_fatigue_score",
            "role": "measure",
            "confidence": 0.93,
            "reason": "Score on 1-10 scale, averaged"
        },
        {
            "column": "sleep_debt_category",
            "role": "dimension",
            "confidence": 0.98,
            "reason": "Low-cardinality status category"
        }
    ]
}