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Sprint Estimation Pointing Scales

Perhaps you’ll agree that Sprint Planning can be… taxing, to put it mildly. It requires practice and patience.

Accurate estimation drives effective planning, and you have a variety of options when choosing an estimation method. The key is finding the one that works best for your team and enables you to build the most accurate sprint projections. While some advanced teams use custom systems, there are a number of tried-and-true options from which to choose.

To get started, let’s take a look at some popular pointing scales.

Modified Fibonacci Sequence
0, ½, 1, 2, 3, 5, 8, 13, 20, 40, 100

You may remember from high school algebra the Fibonacci sequence, a series of numbers in which each number is the sum of the two preceding numbers. For example, 1+2=3, 2+3=5, etc. Modified Fibonacci takes the same basic approach, but includes ½ as an option and then rounds off the higher numbers in the sequence. The rounding in Modified Fibonacci helps reduce the implications of too much specificity.

Scrum pioneer Mike Cohn tells a story in which a team using traditional Fibonacci pointed a story at 21. The Product Owner responded, “Wow, 21, that’s so accurate! You must know exactly how much work is to be done.”

Nailed it.

Story pointing is a team’s best guess given the information they have during planning. Generally speaking, the higher the estimated effort, the less accurate the estimate. A story estimated at 21 is not necessarily accurate, and is assuredly less accurate than a story estimated at 3. The abstraction of the modified sequence reminds both developers and Product Owners that estimates are just that, estimates.

T-Shirt Sizes
XXS, XS, S, M, L, XL, XXL

Framing story effort as t-shirt sizes is great for client-side Product Owners who need to make some hard decisions about a large group of features. For instance, would the PO rather have these four small stories completed or one large story?

It’s particularly useful for POs who are new to estimation, since t-shirts are unlikely to be associated with specific hours. While 5 effort points might be quickly linked to 5 hours or days, a Medium simply offers a relative sense of effort compared to the other stories. Teams can move more quickly through planning when focusing on the big picture, rather than small details.

Capacity Planning

While not strictly an effort pointing scale, capacity planning can be a great tool for teams that are new to Agile and/or to working together. Rather than throwing your team into the proverbial Agile deep end with unfamiliar pointing scales, new teams can determine capacity using a concrete measure everyone understands: time.

In this model, basic arithmetic will serve you well:

Hours/Day x # of Team Members x Days in Sprint = Sprint Capacity

We all know a typical workday is 8 hours, but when was the last time you did 8 full hours of work in the office? Your calculations should include time for standups, brainstorming, vacation, office hijinks… typical team stuff. Assuming 6-6.5 effective hours per team member each day offers a more realistic approach to accurate planning.

Let’s take a five-person team with a two-week sprint that includes one full day for sprint planning and closeout:

6 hrs x 5 people x 9 days = 270-hour capacity

Armed with your capacity, you can start planning. Instead of using relative effort points like the previous scales, the team estimates the number of hours necessary for each prioritized user story. In the long run, teams should move away from capacity planning, but pointing stories in hours can be a great way to understand your collective velocity and learn effective pointing strategies.

Remember that any method you choose takes time and communication to master, and the newer the team, the harder it is to estimate correctly. That’s what the coffee’s for.

What other estimation practices work well for your teams?

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