Why GA4 fields look so trustworthy?

Open a GA4 export and everything feels ready-made. Source, medium, sessions, users — all nicely labeled and tempting to drop straight into reports.

So where’s the real danger? Some fields are purely technical:

• Context-dependent
• Sensitive to implementation
• Never designed for decisions

Using them directly can quietly mislead stakeholders.

What BigQuery reveals instead?

BigQuery exposes raw events, not business truth. GA4 fields are signals, not conclusions. They need interpretation and reconstruction.

My personal rule of survival

If a field wasn’t explicitly defined by the business, I rebuild the metric from raw events. It’s slower — but it keeps my reports defensible.

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