When should Estimation Happen in Scrum?

by StarAgile

December 28, 2020
Category Agile and Scrum

When Should Estimation Happen in Scrum?

The agile estimation is a process where the teams approximates the time taken for project completion and the effort required to be provided to achieve success. Then it is split into multiple tasks and worked with Just-In-Time management. 

There are differences between traditional and agile techniques. The former is time-based and bottom-up whereas the latter are story points based and top-down. 

Affinity Mapping is one way in which the sizing of the efforts of each story point. There are 2 cards kept on the other side of the wall. The estimators are given the choice to select the size of the stories to be placed between the two. The leader must help in clarification of doubts if any. The size depends on the efforts needed for the work to be completed. 

Then the team members change the locations of the user stories as they keep discussing them. The PO then steps in if there are any discrepancies and doubts. Then the PBI's are completed by finally arriving at the consensus. The PO is responsible for prioritizing the items on the board in the backlogs. 

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Why Product Backlog Estimation 

There are several reasons,

• It helps in making long term predictions of how much can be delivered by when?

• It helps in prioritizations of the PBI's

• The team members become aware of the PBI's and how long it takes for each user story.

Why Sprint Backlog Estimation 

• It helps to understand how many and how many tasks to bring into 1 sprint.

• It helps in assessing the workload of each team members

• To coordinate the work better.


When should Estimation Happen in Scrum?

This is a good question, should it be done when the sprint begins? or during the sprint planning, or when the developers bump into the tasks.

Usually, the estimation is done in two levels are for the PBI’s at the story level and the sprint backlog at the task level.

You do the estimate of the user stories in the PBI's when you have prioritized the items and are done with story point estimates as discussed above.

1. Product Backlog estimation (Story level) - You must do the estimate of at least 80% of the PBI's before we start the first sprint. This is story point estimation by making using of different methods discussed above. Then we need to decide how many user stories are good for the first sprint that is the initial velocity or points per iteration. It is good to have a 1-week sprint or 2-week sprint and not a 1-month sprint. The estimation may take a whole day or even 2 days depending on the size of the PBI's. These are subject to changes and are not fixed. It depends on the actual velocity of the team or the actual time taken. The progress is visible to the stakeholders in the form of a burndown chart where the x-axis are the sprints and the y-axis are the story points.

2. Sprint Estimation (Task level) - Here the user stories are converted into tasks and the tasks are estimated in hours. Any task taking more than 8 hours is further broken down into smaller tasks. The result is the sprint backlog. Here the chart that is required is the days of the sprint on the x-axis and the number of hours on the y-axis.

The first estimate that is of user stories is done before the sprint planning which provides the rough estimates. The rough estimates are important than the accurate task estimates, as task estimates are internal to the development team and rough estimates require the product owner's support along with the team's support.

How do Agile Teams Create Estimates?

1. Different values can be used to place the story points as per the values in the bucket. The values are 0,1,2,3,4,5,8,13,20,30,50,100 and 200. These values can be expanded further if needed. The estimators need to select the user stories and then place them in the bucket where the values of the user stories are. Before placing them it is important to discuss the features and requirements of each story. The work must be placed in the bucket based on the consensus. This is reasonable and time-efficient. Learn scrum concepts and principles by enrolling in scrum certification training at StarAgile institute.

2. Voting method is made of a decision-making technique and involves voting by the team members on the product backlog items prioritization. The ranking method is used to order the PBI's with the highest priority in the top to the lowest priority in the bottom. 

This starts with posting all the user stories on the wall or the board. The story descriptions are unique and distinguishable. Each member of the team is given 4 to 5 dots. The team member then posts the dots which are a sticker on the user stories. A leader then uses the user stories with a high number of dots firsts and then users’ stories with the least number of the dots in the bottom. If there is confusion the stories are divided into high, medium, and low then allotted the dots again till the team reaches the consensus. This is suitable when the project is very small and simple. This also is a suitable decision-making tool and a great visualization tool. Take up the CSM certification course at StarAgile and lift your career to new heights.

3. Planning Poker is done by adapting the Fibonacci sequence and story points are used to estimate the difficult tasks. Here the team members will hold cards with story point values that they think appropriate for their tasks. A leader or an administrator will talk about the features and requirements in the hand of that of a project. Know this in detail from here. 

4. Based on the T-shirt size such as extra-small (XS), small (S), medium (M), large (L), extra-large (XL) extra-extra-large (XXL), etc estimates are done. These sizes are used to estimate the story points, depending on the size of each story point. This gives a rough estimate of how much work to do and these can later be converted into numbers. 

The size is decided based on the discussion and the collaborative efforts between the team members. If the estimator's proposed size does not match up then the team voices their opinions and then the team will eventually reach the consensus. This is very easy to adapt when the story point sizes are large. However, it is very subjective as one might not agree with the other on the effort sizes. However, this method is based upon open discussions and everyone will have their say and need to arrive at a consensus.


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