Home Basics Why Mapping Story Points to Hours Will Always Make Your Delivery Predictions Wrong

Why Mapping Story Points to Hours Will Always Make Your Delivery Predictions Wrong

by Srinivas Saripalli

Mapping story points to hours to estimate your work is bad advice when it comes to setting delivery commitments. In reality, revealing this paradox can be done with a fairly easy activity.

Olympia Opaline is a modest, quaint establishment in Navalur, Chennai, INDIA. Those of you who have been following me for a long know that, in addition to reading and coaching, I am also addicted to fast food. Barbeque Nation is a fantastic restaurant close by, and even if it weren’t only 10 kilometres from our home, I’d still go there for our birthdays, anniversaries, and other important events. It’s also become my favourite spot to meet with potential customers interested in using Nave in their company.

I went there a few months ago to meet with the technical director of a large media business, shortly before pandemic precautions forced the place to close. We were discussing their main issue – lack of consistency – over a drink of some name-brand cocktail.

“When we meet with the teams and they say this tale is 2 storey points, I do the arithmetic in my head (1 point equals approx. 3 days) and I know right away it will take 6 days,” she added. If they claim the storey is 8 points, that means it will take roughly 3 weeks to complete. However, I don’t see why this strategy usually fails!”

So, let’s get a little more into it!

Compare the Story Points of Completed Stories to the Cycle Time of the Stories

Before we get started, let us just clarify when we refer about cycle time, we’re referring to the amount of time that passes between the start and conclusion of a work item.

Kanban Lead Time
Kanban Lead Time

Let’s do a little practise. Let’s make a scatterplot with the X-axis representing storey points and the Y-axis representing cycle time. On the X-axis, we’ll specify 1, 2, 3, 5, and 8 points (you can adjust these values based on your own context). Let’s see how many days it took to finish a storey with three storey points. In this case, it took 12 days to complete the storey.


Now, for the last 20 to 30 finished stories, let’s map storey points to hours. In the “Story points to hours correlation” spreadsheet, enter the storey points for each work item in column B, and then enter the actual cycle time to complete the item in column C.

Moving on, we can expect items with 1 narrative point to be rather quick to complete, and as the storey point value increases, the time it takes to complete an item will climb gradually.

For one of the media company development teams we discussed in Barbeque Nation, the relationship between storey points and cycle times looks like this:

Story Points to Hours
Story Points to Hours all data points

When it comes to cycle times, goods with one storey point can take anywhere from one day to 22 days. The same results can be seen for products with two and three storey points. The most striking trend is that their 8-point articles are from the same time period as the 1-point things.

Use the “Story points to hours correlation” spreadsheet to map your own data and see if there’s a link between storey point estimation and the time it takes to complete your project. The chart’s primary function is to demonstrate that storey points should not be linked to hours. This is supposed to be a one-time effort, with the hopes that the results will put this nasty practise into question. The greatest way to communicate the fact that converting storey points to hours will get you in trouble is to provide proof based on your previous performance.

Are you getting the most bang for your buck with storey points?

It’s self-evident that converting storey points to hours isn’t a dependable way to make delivery commitments. In fact, you should never use storey point estimate again; there are far more effective options that will allow you to make accurate future forecasts.

Now the question is whether you’re getting the most out of your storey points.

When it comes to storey points, the amount shouldn’t matter all that much. The most important thing is to have a talk about what needs to be done and how you may go about doing it. In fact, one of the most important advantages of storey points is that they start a conversation.

It’s important to distinguish between the analytical and forecasting processes. Consider how much time you waste debating if something should be worth 5 or 8 points. If you have a team of ten individuals and spend one hour per week estimating your work with storey points, that’s ten hours per week you might be performing actual work. Understanding the problem you’re attempting to tackle is critical. The points themselves are not the issue. If any of this sounds familiar, it’s worth questioning your existing practise and looking for a different way to start these dialogues.

Last but not least, discussing storey aspects is not the best technique to communicate with your customers. Have you ever tried to explain what “8 storey points” means to a customer? Estimating storey points is a foreign language to them. Your customers aren’t thinking in storey points. They think in terms of elapsed time and the question, “When will this be finished?”

We delve deeper into the proven tactics that enable you to confidently answer the question “When will this be done?” and satisfy your customers’ expectations in our Sustainable Predictability programme.

It’s Horrible Advice to Convert Story Points to Hours

Even though many management tools have the ability to tie tale points to hours, don’t fall into this trap. It will only jeopardise your ability to produce accurate delivery estimates.

Use storey points to start a discussion about the work that needs to be done so that you can come up with the most practical answer that benefits your consumers. And always remember that time spent actually doing the task is far more useful than time spent debating the numbers behind the work.

Recommended Reading: Concentrate on quality rather than agile velocity as the sole metric.

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