Most of you who have worked with traditional software development model know how to estimate for the project provided you follow the same traditional software development method. We often get stuck in debating how many sprints it would take to complete the project. If you are executing a fixed price project using Scrum, then it becomes more important to providing the estimation to estimate project cost. Here in this post we provide some simple steps that can be followed to arrive at the over all estimate for the product backlog.
1. Estimate the size of each Product Backlog Item by Planning Poker.
SIZE = Effort x Complexity x Uncertainty
Planning Poker to estimate the Product Backlog
everyone reads the product backlog item
Each person picks up the size estimate relative to the product item that has already been estimated. Normally this is the smallest estimate in the product
Everyone shows the card at the same time
if there is a significant variation in the estimates, then high and low are explained
repeat the process up to 3 times until estimates stops to converge
pick a number that everyone agrees to
2. Total the Product Backlog Estimation and you get the total of size. Say in our example, the total is 300 i.e full list = 300
3. Consider the teams velocity as 26 per sprint
4. Whole backlog would take 300/26 = 11.53 Sprints
5. Add Estimation buffer of 10 to 15% depending on your comfortless on the estimates. In our example we consider 15% Estimation buffer
15% Estimation Buffer = 15% of 11.53 = 1.73
6. Add rework buffer of 10% as you would expect to have some rework
10% Rework Buffer = 10% of 11.53 = 1.15
7. Add additional buffer of 10% to cover any risks
10% Additional Buffer = 10% of 11.53 = 1.15
8. Add 1 sprint as Pre-Release Sprint
9. Total Sprints needed for the project = 11.53 + 1.73 + 1.15 + 1.15 + 1 = 16.56 ~ 17 Sprints
10. You would need 17 Sprints for a Product Backlog of Size 300, and team operating at a velocity of 26 per sprint.
Hope these simple steps will guide you to estimate your project.
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