What metrics would you measure for a new feature on WhatsApp?

This question is asking you to consider the types of metrics you would use to measure the success of a new feature on WhatsApp. The interviewer wants to assess your analytical skills, as well as your understanding of the type of metrics that would be relevant for a mobile app feature and how these could be tracked to determine if the feature is successful or not. When considering metrics, it will be useful to think along the lines of user engagement, feature adoption and user satisfaction. Remember to justify why you would focus on these particular metrics.

To measure the success of a new feature on WhatsApp, one could consider the following metrics:

1. User Adoption Rate - This is the overall number of users who actively use the new feature after its launch. A high adoption rate indicates the feature are useful and easy to use.

2. User Engagement - Metrics like the frequency of use, duration of use, and actions taken while using the feature (for instance, if the feature is a sticker pack, how many stickers are being used daily?)

3. User Satisfaction - Surveys or feedback forms can be used to gauge user satisfaction with the new feature. This can provide valuable insights that quantitative metrics may miss.

4. Retention Rate - How many users continue to use the feature after initial adoption? A high retention rate would suggest the feature provides sustained value to users.

In addition, any direct or indirect increase in user base or user activity on the app due to this feature would also help measure its impact.

When examining the effectiveness of a new feature on WhatsApp, I would consider these metrics:

1. Daily Active Users (DAU) / Monthly Active Users (MAU) ratio: The DAU/MAU ratio offers insight into how often users are engaging with the new feature on a daily basis.

2. Feature Adoption Rate: Measures the percentage of total users who have started using new feature after its release.

3. Average Session Duration: This can help quantify the extent of user engagement. For instance, if we're looking at a new group video call feature, the average duration of the video calls would be a key indicator of its success.

4. Customer Churn Rate: If there's an increase in churn rate after the release of the new feature, it could be an indication that the new feature is not being well received.

Lastly, it's important to examine any effects the feature has had on the overall growth or stickiness of the app. Has it led to an increase in user referrals or a decrease in user churn? The answers to these questions can provide a comprehensive picture of the performance of the feature.