The apex of the #deletefacebook movement took place from March 18-24 2018, following the news of the Cambridge Analytica scandal (cited here). During this week we noticed a significant rise in CPM (Cost per 1000 Impressions.) CPM best helps us get an idea of how many people were on Facebook that week. As is evident below, the CPM (first column) during the peak week of the scandal was an astronomical, $29.87.
To compare and contrast, during the previous week of March 11-18 the CPM was $23.91. A significant drop and a sign that some users were using the platform less the week of the scandal (March 18-24) than previous weeks.
To further illustrate this point, we have gone back to the third week of January (18-24), way before news of this scandal and see a CPM of $17.22 (below), far less than the week of the scandal at $29.87. It seems that people’s time on the platform may have been affected during this peak week in March, but slowly people returned to the platform in subsequent weeks.