Decomposition
Reusable drop-off hunter. Two cubes from GA4: Channel × Device × User type (67 cells) and Landing page × Device (268 cells). Pick a baseline period and a comparison period; the table sorts rows by the biggest absolute change and flags contribution to the total.
Method
Contribution / decomposition analysis
Big cells with big deltas drive the KPI. Small cells are noise.
Best practice
Rank by absolute delta × baseline volume
A 50% drop in a 0.1 tx/day cell doesn't matter. A 15% drop in a 6 tx/day cell does.
Watch for
Simpson's paradox
Overall trend can hide subgroup effects going opposite directions.
Channel × Device × User type
—| Cell | Base sess/d | Cmp sess/d | Base tx/d | Cmp tx/d | Δ tx | Δ % | Base $/d | Cmp $/d | Δ $/d |
|---|
Landing page × Device
—| Cell | Base sess/d | Cmp sess/d | Base tx/d | Cmp tx/d | Δ tx | Δ % | Base $/d | Cmp $/d | Δ $/d |
|---|