Managers , take it easy. In many organizations there is an urgency to measure, look at numbers as they move to scrum within the first two sprints. As a general guideline, do not take too much notice of the statistics for four or five sprints.

Teams take a while to form and norm. They also make a lot of mistakes and tend to work a lot harder in the beginning.  Remember the Agile priciple

Simplicity–the art of maximizing the amount
of work not done–is essential

Teams take a while to master this. Once they have this and resoved team forming, norming, that would be a good time to start comparing them with others.

This question comes up a lot in new scrum teams. The adjustment from a couple of months to two weeks is very tough indeed. Generally speaking do not keep changing the sprint length. One Sprint two weeks, the next three weeks etc.

One of the main tenets of Scrum is “Sustainable pace”. Scrum teaams are able to get to this sustainable pace as they get really good at delivering something in a short span of time ie, 2 or three weeks.

Velocity cannot be precicted well if the Sprint length changes. If you think changing 2 to three weeks is going to help you, you are mistaken. The team will only end up signing of for more work than they normally would. Hence the problem has really not gone away.