In our earlier post How to Do Project Estimates In Scrum – Estimation for Fixed Price Projects we had looked at estimation for fixed price projects. In this post we look at some practical issues while estimating and providing an upfront commitment on the scope of the project but there isn’t enough info to estimate for the projects ( which is in most cases!).
While doing an estimates and commit to the number of sprints it would take to delivery a defined scope, all it boils down is to estimate the velocity. Two common problem we face while estimation of velocity is that (1) There is no velocity data for the team (2) There is no team in place yet ( the project is probably in the proposal stage)
(1) There is no velocity data for the team
Let’s assume you have the team but don’t have any velocity data to estimate. Here are the steps you should be following:
1. Have them estimate for stories in story points the normal way for all the stories in the defined scope. Do this even if the team has no idea what their velocity will be.
2, Calculate the sum of the story points for all the stories, lets say 500 points.
3. Now have the team plan a sprint.
This is done by starting with one story, split it into tasks, estimate the tasks in hours and ask the team if they can commit to finishing it. Then repeat with additional user stories until the sprint is full.
4. Assume the team does this and commits to stories A, B and C.Now you have points on all the stories including A, B and C say 18.
5. Add the points on those three stories and that’s a starting point for velocity.
6. You can get the team to repeat by planning another sprint and commit to Stories W, X, Y and Z, which is probably a different number of points say 22.
7. Now you have two values as a range. Say 18 points ( for stories A,B and C) to 22 points ( for stories W,X,Y and Z).
8. Take the velocity by adjusting based on your intuition. If you think the team is about to over commit in their early sprints, use the velocity value at the lower range of estimates i.e 18.
9. Number of sprints to deliver the defined scope = sum of story points i.e 500 / lower range of velocity i.e 18 = about 28 sprints.
10 Add about 10% buffer and round it off to 31 sprints
(2) There is no team in place yet
Let us consider a situation where you don’t even have the team yet and obviously no velocity data. You’ve got plenty of employees in the pool but you don’t know who will do this project.
1. In this case, first workout the profile of the project team like the number of junior programmers, senior engineers , lead engineers etc.
2. Now get some representative people together from the pool, similar to the team profile you have worked out
3. Have the representative team pretend to be the team that will be working and do the same steps “There is no velocity data for the team”
The buffer can be added based on your intuition. A more accurate way would be to take velocity date from other teams, calculate the relative standard deviation ( i.e standard deviation in percentages )
Average those relative standard deviations over all teams and use the percentage as a buffer for the new team.
So, now know have the get the baseline plan/schedule i.e the number of sprints to deliver a defined scope even if you don’t have the velocity data or the team in place.
