Anonymous
First I would clarify what kind of notification is it—is it a notification for when users get a new friend request? How does this new system differ from what existed previously. Then I would examine how this new notification has been rolled out. Specifically, is this update now live for only one country or region? Also, is this notification for only particular users of the app (i.e. is it only for mobile users or the Facebook app or does it include desktop/laptop users?) Given this information I can examine potential subgroups that may be driving this drop in friend request acceptances—for instance when examining device type there could be one mobile type that has a significant percentage drop in acceptances while others are more stable, suggesting that the notification a design flaw or bug with that type of device. Metrics I would consider include not just the overall percentage decrease in friend requests accepted (requests accepted/total friend requests), but also the click through rate of the initial notification. If the latter has dropped as well, then that would suggest a poor design of the initial notification itself. Additionally, aside from examining subgroups, I’d want to consider what time period was examined showing this drop—meaning I want to make sure it was sudden and correlated with the notification launch rather than a time of year that has traditionally low friend request acceptances.
