Who should take scrum metrics?

Who is the first team member with the capacity to do that work and recognizes that it needs to be done?

And in addtion to Ian: who needs these metrics and why?

who needs these metrics and why?

And more specifically, what do they want to learn from these metrics?

Thanks for the answers. These metrics are mostly to improve team performance, so the idea is to gather them to get information on what to do to make the development team better.

To expand on the (very good) questions asked by others, I would expect that the Scrum Master would be involved in determining who is asking for these metrics, why they feel these metrics are necessary, and what their objective is. One of the roles of the Scrum Master is to coach the Product Owner, the Development Team, the organization, and the stakeholders. Rather than just blindly producing metrics and reporting, the best thing to do is to understand the problem and work with whoever is asking for the metrics to get the best possible information that can help them solve their problems with the least amount of unnecessary or additional work.

Assuming that you've done all of this and have identified a metric that is necessary, the next step would also fall to the Scrum Master to help get the team over any impediments that lead to the collection of the data required or production of the reporting that was asked for. This could be done within the team, but it may also require working with people outside of the development team.

Depending on what the metric is, I can see it falling to either the Development Team, the Product Owner, or the Scrum Master to collect. Even if it falls to the Development Team or Product Owner, I can see them asking for help from the Scrum Master to improve their ability to collect the information or to otherwise facilitate the process.

Thank you so much for your answer Thomas! Very well explained!