Explain why a metric moved

Decomposes a period-over-period change in one metric across campaigns, devices, networks, countries and search terms, and ranks the segments by how much of the total change each one accounts for. Use when: the user says something dropped, spiked or "looks wrong" and wants to know why. This is the right first tool for that question. Do not use when: the user just wants the numbers (google_get_campaign_performance) or a single dimension they already suspect (google_get_device_performance, google_get_geo_performance). Returns, per dimension, the segments that moved most, with their share of the total change. Read the top one or two lines and say what they mean — a change concentrated in one campaign is an account change, one spread evenly across every dimension is usually seasonality or an auction-wide shift you did not cause. Two cautions worth repeating to the user: a short window makes everything look dramatic, and conversions keep arriving for days after the click, so the most recent days always look worse than they will turn out to be. If you are unsure which account, campaign or period the user means, ask them — do not guess ids or dates.