How the What's Changed Report is Calculated

What's Changed uses advanced statistical techniques to calculate significant changes in the underlying site. Beyond this, it's a secret.

Why do I have 'falling' entries that are actually increasing and vice versa?

Sometimes the What's Changed Report will report an item in the Top Rising list that is actually falling and an item in the Top Falling list that is actually rising. This happens when the total number of visitors significantly changes across the same time period. If the total number of visitors falls from the first to the second time period and a campaign gets slightly fewer clicks across the time periods, the campaign may show up as the top rising, even though it's less. This is because although the campaign has, in absolute terms, fewer clicks, it has increased relative to the total number of visitors.