Case: a mobile e-commerce app where users add items to the cart but do not complete the purchase. Hypothesis: send a push notification 30 minutes after leaving the app with a full cart. What metrics would you investigate?

To test the hypothesis and evaluate the effectiveness of push notifications, it is important to investigate the following metrics:

• Number of users with a full cart who left the app — to understand the target audience size for notifications.
• Time from leaving the app to sending the notification — to verify that 30 minutes is optimal.
• CTR (Click-Through Rate) for push notifications — how many users opened the app after receiving the notification.
• Conversion to purchase after notification — how many users completed an order after receiving the push.
• Overall change in the purchase completion rate — comparison with a control group without notifications.
• Unsubscriptions from notifications and negative reactions — to assess the impact on user experience.

It is also useful to segment users by activity, type of items in the cart, and time of day for more precise notification settings.