August 9, 2019
Earlier this year, we let you know about our updates to ad units and that we'd be removing ad unit experiments. To make way for new experiment types and a cleaner user experience, we'll now remove your old ad unit experiments from your "Experiments" page on September 15, 2019.
If you'd like to save your experiment results, we recommend that you visit your "Experiments" page and click Download data before this date.