Explain a change in Meta performance

Compares a window with the equally long window before it and attributes the change to the ad sets, placements, countries or age-and-gender groups that caused it. Use when: a number moved and the user wants to know why, before changing anything. Do not present the biggest row as the cause on its own — check its share of the move, which the table reports. A change spread thinly across everything usually means an auction or seasonality shift, not something inside the account. Do not use it to compare two arbitrary periods of different lengths; the comparison window is always the same number of days, immediately before. Returns the total before and after, the rows that account for most of the move, and each row's contribution. If nothing explains more than about a sixth of the change, the tool says so instead of inventing a cause.