Estimating Vs Forecasting : Demystifying in Agile Projects (Part 2)
Continued from the last post
Estimating Vs Forecasting : Demystifying in Agile Projects (Part 1)
Sitting in CSPO class, heard that in present agile projects, it’s customary to forecast rather than estimate?
So how to Forecast (With Charts) :
Most of the teams uses the following . There are two main inputs to the forecast.
1) Sum of Story Points ( of individual features). Take the estimates for all the features in the backlog, a rough estimate will do, or all the features in the next release , again rough. estimate. This could be facilitated in a 2 hour estimation session.
2) The Team Velocity ( Projected for 3 weeks or 1 week will do)
With these two in mind, most teams create forecast by showing a sprint by sprint” burn up Chart” of work completed. Plots the actual cumulative work completed, and then use the velocity to create a what is called a “forecast line” for the completion of the rest of the features in the release.But these charts shows the output and not the outcome.
One can draw a Optimistic and a Pessimistic trend line.
The gap between the Optimistic and Pessimistic trend line shows how unpredictable the team velocity is which usually becomes stable over time.
The release line ie Fixed line in the chart is what is required for the Release (ie a in 3 months or 6 Months) . So there are couple of questions to be asked here for the forecast ie
a) When (Fixed Scope)
b) What (Fixed Time) and
c) When and What (Fixed Scope, Fixed Time )
Lets check these questions
a)When Question: If the question is when all the items that total 500 SP will be done, then its the intersection of the trend line and the fixed line as shown (In BOLD)
b) What Question: If the question is What all the items that will be done say by Sprint 3 or lets say ‘Black Friday” , then its the intersection of the trend line and the fixed line as shown (In BOLD ORANGE)
c) What and When Question: If the question is What all the items that will be done and by What time ? ie say by SP 500 and by Sprint 3 or lets say Will these feature items be done by ‘Black Friday” , then its the intersection of the trend line and the fixed line as shown (In BOLD BLUE)
Also note that the Release Size may increase/decrease (Dotted Line Below) over sprints as items are added or removed. But the concept of forecasting will remain the same
So in a nutshell , forecasting is sum of what is required and what is to be delivered. In scenarios where there are multiple teams, its basically a sum of multiple teams velocity/charts but with additional problems of dependencies/integrations . For this technical debt, architecture and branching strategy are key to be synchronised .
For real world example of how to estimate, read my other post.