What’s a Story Point

What is it?

Story Point is an arbitrary unit of measurement to measure amount of work in a Sprint. It’s a pretty abstract concept and can be very hard for people to comprehend. Is it same as hours? No. Similar then? May be.

What is it then? It is something that you can relate to Sprint to Sprint. If your team accomplished x story points in one Sprint, given the same amount of resources and time, team should be able to accomplish more or less the same next Sprints. Once you do it a couple of times, you should be able to get your team Velocity.

Other Industries

If you take a look into Construction or Manufacturing industry, the measurements are pretty accurate and pretty standard. Everybody know what an 1 mm drill is (if there such a thing :)). You go to Home Depot, every part has measurable characteristics:  height, weight, width, color, etc. Why shouldn’t your Scrum Team be: Resources, Duration, Sprint Goal, Story Points, and Velocity.

Story Points are usually based a mathematical number series called as Fibonacci Sequence.

Fibonacci Sequence

Wikipedia has a good read on what they are. It essentially are numbers as 1, 2, 3, 5, 8, 13, 20. Note number on right is addition of last two numbers on left 8 = 3 + 5, 13 = 5 + 8.

Each PBI (Product Backlog Item) is supposed to have Story Points associated. This is done by a voting process (sounds funny, but it’s important). Only Pigs (Team members responsible for building the feature Dev, QA, UI/UX, Doc) are allowed to vote.

Voting is also referred as Planning Poker. Why Poker: Because Pigs don’t know what other Pigs have selected unless “Show” is called by.

Voting (Planning Poker)

During the Sprint Planning meet, the Product Owner spends about a minute explaining the PBI  that needs to be have Story Points assigned. In the next minute or two Pigs  ask questions to get clarity. Note: This is not a feature discussion meeting. Pigs and Product Owner should have a good idea about the PBIs prior to the meet. What you are trying to do is assign Story Points, so you can predict future Velocity.

Each Pig is handed over a deck of cards. There are seven cards in the deck with each containing one of these numbers: 1, 2, 3, 5, 8, 13 and 20. When asked to vote, each Pig should individually select a card and put it on the table face down. When asked to show, everyone should show their cards together. People on the phone are asked to tell first so they don’t get influenced by the outcome of physical cards.

Story Point Guidelines

This is the most important aspect of allocating Story Points. Every team member must know how to pick one of those Fibonacci numbers. It might be a bit easier if you think from an elimination point of view.

20 – Too big for the Sprint. You need to break the PBI into smaller PBIs. Ideally nobody should have selected this number in voting. If they have then be prepared to talk about it.

13 – Something that will take full Sprint to accomplish. You should also be very clear what exactly does done mean for the PBI. Is it just Code Complete, or does it include QA and Documentation. Ideally PBIs should be created in such a way that the Product becomes releasable at the end of Sprint. However, this may not be very practical. I’ll table that discussions for a future Blog. For now keep in mind that you need to assign 13 if you think this will be going on through out during the Sprint by 1 person. In a 15 day Sprint: 8 days for Dev, 4 days for QA, 1 day for Doc.

8 – Something that takes half the Sprint.

5 – 5 days (in a 3 week Sprint)

3 – 3 days (in a 3 week Sprint)

2 – 2 days

1 – 1 day or less

less than 0 – Combine such PBIs into 1 or more

Again, your definition may differ depending on duration of the Sprint. The above is based on a 3 week Sprint. With lots of experimentation we’ve concluded that 3 weeks Sprint is the best. Perhaps another blog to talk about that.

What you really need is a framework to which your team members can associate these numbers to. A 5 may be 3 days in your company.

During the first few Sprint your team members may be asking questions as: What does 3 mean again? and 5..hmmm.. how about 13. I don’t have card for 10? That’s perfectly normal to ask.

Re-Voting

It’s unlikely that everyone will come to the same number on the very first voting. It may be possible that majority come with same numbers with a few on the extremes.

People voted on the extremes should be asked to explain their rationale. After listening to arguments and arguments team should vote again. Move on to the next PBI as soon as you hit a consensus. Again it’s not necessary that everyone has the same number. In the interest of keep moving in the meeting you may pick the number with majority of the votes and continue on to next PBI. With time you’ll get better with all this.

IMO you should not go beyond two rounds of voting (including the first round) for a PBI. If you need multiple rounds then there is a bigger problem. People should have a good understanding of the PBI prior to coming to the Sprint Planning meeting. Focus on solving that problem first.

Total Story Points

At the end of the Sprint Planning meet you should total all the Story Points of individual PBIs and find out what the total is. This total is very important. Total will dictate your Velocity. If you did x this Sprint, you should be able x next Sprint and so on.

Still not convinced

Well, you are not alone, I struggled for a long time. All I can say is keep practicing and you will get it.

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