The Engagement API delivers invaluable impression and engagement metrics that enable you to monitor the performance of your activity on Twitter.
In our continual effort to enable marketing decisions based on our data, we are excited to share recent changes to the Engagement API that provide greater consistency with metrics across all of Twitter. We recently deployed changes to modernize the Engagement API to use the same metrics aggregation methodology in use by the Twitter analytics dashboard.
We took a thoughtful approach to try and minimize breaking API changes when rolling out these new metrics and deployed these changes on October 9, 2017.
These changes will improve consistency from all of the places you or your customers might monitor your performance on Twitter. You can find the detailed outline of changes here.