{
  "kind": "report_reference",
  "report": "Traffic acquisition with device comparison",
  "location": "Reports > Acquisition > Traffic acquisition",
  "dimensions": [
    "Device category"
  ],
  "metrics": [
    "Sessions",
    "Engagement rate",
    "Key events",
    "Key event rate"
  ],
  "checkpoints": [
    "Plain table read first",
    "First group defined by one dimension",
    "Second group defined by the same dimension",
    "Rate columns read beside session columns",
    "Baseline kept for context"
  ],
  "guide": "report-comparisons-build",
  "title": "Compare two groups in a GA4 report: build a comparison and read what actually differs",
  "worked_example": {
    "rows": [
      {
        "row": "Mobile",
        "sessions": 2610,
        "engaged_sessions": 1305,
        "key_events": 118,
        "revenue": "2140.00"
      },
      {
        "row": "Desktop",
        "sessions": 1780,
        "engaged_sessions": 1246,
        "key_events": 142,
        "revenue": "3280.50"
      }
    ],
    "totals_recomputed": {
      "sessions": 4390,
      "engaged": 2551,
      "engagement_rate": "58.1",
      "key_events": 260,
      "key_event_rate": "5.9",
      "revenue": "5420.50",
      "revenue_per_session": "1.23"
    }
  },
  "verification": "Figures recomputed in Python 3 with decimal arithmetic, 2026-11-11. No live GA4 run."
}