Top 5 Scrum Estimation Techniques

Estimation, the very word in itself seems quite heavy, and it does feel substantial when you are asked to estimate unfamiliar items to some degree. One of the key advantages of adoption Agile is the capability of the team to estimate work effectually. Earlier when the teams were on waterfall, they used bottom-up approach with the smallest tasks at the bottom, in order to determine the cost of each feature.

On the contrary, Agile uses two estimation techniques, such as Top-Down Estimation and Relative Sizing, since we are not concerned about the detail of the tasks. Instead, we are much more interested in swift estimates of higher-level features or even epics.

What is Estimation?

“Estimation (or estimating) is the process of finding an estimate, or approximation, which is a value usable for some purpose even if input data may be incomplete, uncertain, or unstable. The value is nonetheless usable because it is derived from the best information available.”

As a part of the Scrum process, the development team sits together in the planning session, pulls out the items as per priority from the backlog and associates an estimate to the PBI (Product backlog item). The size of the PBI is projected in terms of User Story Points.

Estimation is necessary for any planning practice.

Why to Estimate?

Some reasons could be::

• To get people liable for their work

• To predict the finish line

• To fill up the sprint with work

• To measure teams’ progress, we do an estimation.

But in true sense, estimates are required to plan work and time. It even helps the team to measure success in terms of numbers. Yes, they do project success, through velocity, sustained velocity figures, up rise in the numbers. Estimates can be turned into release plans too!! Even they help you make weighty decisions.

“Estimating isn’t about estimating at all. Estimating is about creating a shared understanding of the requirements and a shared understanding of the solution. When teams have problems estimating, it is almost never an estimating problem, it is a shared understanding problem” - MIKE COTTMEYER

How to Estimate?

Estimating work items for new teams get quite difficult as the teams are unfamiliar with the requirements and require solution but over time, as team members get used to the product, they develop a progressively precise sense of how they are going to approach stories and how much effort each user story will take to complete.

As human beings, we are typically good at relatively estimating the items, e.g., we cannot predict at first instance if the Earth is heavier than Mercury, because heaviness is dependent on density which is not a visual thing to determine but we can confidently say that the circumference of Earth is bigger than that of Mercury as size can be determined easily by visualization. Hence, we can relatively estimate the size of earth in comparison to the Mercury just by looking at it. Let’s consider the image below which shows how the product can be estimated.

Teams across the world use a variety of methods to estimate their work. You just have to find the right way or the way most suitable for your team’s needs. There is no fixed rule for estimation and luckily, we live on a planet where options are not scarce, and this applies to estimation as well.

Types of Estimation Techniques

Accordingly, we will now be discussing some of the methods which are usually used with the teams. Start off with the one which is being widely used across the globe:

1)    Planning Poker

Planning Poker is an Agile estimating and planning technique that is based on an agreement from the team on the points being assigned to the PBI. It makes sure that everyone participates and that every individual in the team shares his/her opinion.

To start with, each team member is given a set of cards with numbers on them. The numbers are usually in the Fibonacci sequence: 0, 1, 2, 3, 5, 8, 13, and 21. The Product Owner reads out the story, after which everybody in the team is asked to hold up the card showing the level of effort that they believe this story holds.

Once all the votes are in, the team members with the lowest and highest estimates explain why they choose their numbers. The team then re-estimates as per the new perceptions discussed. Once the agreement has been reached that score is recorded with the story to which it relates, the team is good to proceed.

2) T-Shirt Sizes

This is a seamless technique for estimating a huge backlog of relatively large items. T-shirt sizing is based on binning- a technique for accurately grouping together items of similar size. The bins are typically allocated labels matching those commonly used with T-shirt sizes: extra small, small, medium, large, extra-large, etc.

In a similar way, a few categories are created for the Product Backlog items being estimated. One set of categories could be Simple, Medium Complex, Complex, Very complex and so on. For each PBI, the team decides which category it should be put into

The primary advantage of t-shirt sizes is the ease of getting started. T-shirt sizes can be a great way of becoming familiar with relative estimating. So, you can start with it if your team finds that easier.

3) The Bucket System

Much quicker than planning poker is the Bucket System. This system is a decent substitute when estimating a large number of items with a large group of participants quickly. Different buckets are created with values: 0,1,2,3,4,5,8,13,20,30,50,100, 200. The stories need to be placed within these where the estimator finds them suitable. The group estimates the items by placing them in these “buckets”.

Buckets are usually different sheets of brown paper where you can place the sticky note with the item. But you can also use actual baskets to limit discussion about already processed items.

4) Large/Uncertain/Small

A very fast method of rough estimation is the Large/Uncertain/Small method. The team categorizes the items as large/Uncertain/Small, starting with populating the extreme categories. Following this, the group can discuss the more intricate items. This is actually a generalization of the bucket system. The system is especially good to use in smaller groups with comparable items.

 

5)    Dot Voting

When there is a relatively small set of items and you don’t want any complex techniques, you can opt for Dot Voting. This method has been coined from decision-making and can be used for estimating. Each person gets a small number of stickers and can choose to vote for the individual items. The more dots, the bigger the size. This method is very simple and fast; it will work effectively to assess a small number of stories (up to 8-10).

Conclusion

There are many techniques that the teams use globally to estimate their work, here, we have discussed the top five, but there is no consensus over which method is best. Each method has its own advantages and has been customized as per the team’s functioning pattern. Like there is no common medicine that applies to all ailments, in the same way, there is no single method that applies to all for estimating.

A facilitator must understand that estimation takes time to sink in with the teams, and it should not be forced upon them. Go for the one that best suits your team’s needs and, simultaneously, can provide optimum results.  

Credits: Scrum.Org