dropped stories during the sprint and velocity measure
Let's say that at the beginning of the sprint the team commited to 5 stories of 10 story points each. The ideal team velocity for that particular sprint is 50 if all stories are done. In the middle of the sprint the team agrees with PO to drop 2 of the stories and add another one from backlog of 5 story points. If the sprint is finished with all the other stories completed (30 story points) and the adhoc one of 5 points what is the teams velocity? Is it 35 or 30 based on the original commitment??
If the 5-pointer they added is of value to the Product Owner, can you think of any reason not to take it into account when ascertaining the team's velocity for that product?
Why though would a team commit to stories of a certain estimated size? What sort of commitment is that, and why would it be useful? Aren't stories planned into a Sprint just a forecast of the work thought necessary to meet the Sprint Goal?