The Performance Analyzer lets you easily compare your data across two timeframes. This comparison allows you to quickly see what drove the changes and identify major contributors, as well as zoom into each metric.

To access the tool, from the Dashboard proceed to Performance → Performance Analyzer. Select the type of the campaigns, select one or multiple campaigns, and choose timeframes for comparison. Now, click on the Compare button. 

When you have the results, it’s easy to see what drove the changes in the account and how the various metrics interact. With this tool, you can click on each metric to see a detailed comparison by campaign, adgroup or keyword.