If you don’t know about User Stories, now is the right time to understand the concept before reading up the concept of story points.
Every user story has story points assigned to it which reflects the effort it would take to complete the user story. However, note that story points is not an exact effort estimate or a completion date estimate. Also, story points do not determine in which order the features will be delivered. Assigning a point value to each story is basically based on how big it is as compared to other stories. By focusing on relative size of features and not the exact amount of time, the scrum team stays engaged and is allowed for uncertainty in their plans.
In order to make this work, scrum team picks a number of points that indicates the amount of effort required for each story. This exercise is repeated for each story in the sprint backlog so that all stories have an assigned number. With this number, the team is not trying to predict how much time it will take to build the feature, instead the team assigns a point value to each story based on its size relative to other features that they’ve built in the past.
Some teams take reference of T-Shirt sizes to assign story points. For example, they can use 1 point for XS, 2 points for S, 3 for M and so on. Some teams use Fibonacci sequence i.e. 1, 2, 3, 5, 8, 13, 21… if they believe it provides a more realistic weight for bigger features. The team gets better at using the scale as long as they use the scale consistently.
Total number of story points completed in a sprint determines the sprint velocity. If the team completes 10 user stories totaling 50 story points, 50 story points is the velocity that the team can use to plan for next sprint (and not 10 user stories!).
There is obviously a learning curve to all this and the team gets better at assigning story points and the number of points they can deliver in each sprint as they gain more experience.
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