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What Are Story Factors?


Story factors are a unit of measure for expressing an estimate of the general effort that shall be required to totally implement a product backlog merchandise or another piece of labor.

After we estimate with story factors, we assign a degree worth to every merchandise. The uncooked values we assign are unimportant: Some groups use a modified fibonacci sequence (1, 2, 3, 5, 8, 13); others use a doubling sequence (1, 2, 4, 8, 16). 

What issues are the relative values. A consumer story that’s assigned two story factors ought to be twice as a lot effort as a one-point story. It must also be two-thirds the hassle of a narrative that’s estimated as three story factors.

As a substitute of assigning 1, 2 and three, that workforce may as an alternative have assigned 100, 200 and 300. Or 1 million, 2 million and three million. It’s the ratios that matter, not the precise numbers.

One of many principal causes story factors are so beneficial is that they permit workforce members with completely different ability ranges to speak about and agree on an estimate. As a substitute of arguing about how lengthy it would take every workforce member personally to do one thing, groups as an alternative can shortly say that this consumer story is about twice or thrice as a lot effort as that consumer story. With story factors, it’s all relative.  


Methods to Calculate Story Factors in Agile

The most effective definition of story factors is that they characterize the effort to develop a consumer story or product backlog merchandise.

Effort is a query of time: how lengthy it should take to complete one thing. Many elements go into figuring out effort, together with

  • The quantity of labor to do
  • The complexity of the work
  • Any threat or uncertainty in doing the work

When estimating with story factors, many issues come into play: complexity, effort, threat, and quantity. However in the end, story factors are an estimate of effort. 

Let’s see how every issue impacts the hassle estimate given by story factors. For every issue that goes into selecting story factors, examples are supplied to assist improve understanding.

The Quantity of Work to Do

Definitely, if there’s extra to do of one thing, the estimate of effort ought to be bigger. Think about the case of creating two internet pages. The primary web page has just one discipline and a label asking to enter a reputation. The second web page has 100 fields to additionally merely be crammed with a little bit of textual content.

The second web page isn’t any extra advanced. There are not any interactions among the many fields and every is nothing greater than a little bit of textual content. There’s no further threat on the second web page. The one distinction between these two pages is that there’s extra to do on the second web page.

The second web page ought to be given extra story factors. It most likely doesn’t get 100 occasions extra factors though there are 100 occasions as many fields. There are, in spite of everything, economies of scale and perhaps making the second web page is barely 2 or 3 or 10 occasions as a lot effort as the primary web page.

Threat and Uncertainty

The quantity of threat and uncertainty in a product backlog merchandise ought to have an effect on the story level estimate given to the merchandise.

If a workforce is requested to estimate a product backlog merchandise and the stakeholder asking for it’s unclear about what shall be wanted, that uncertainty ought to be mirrored within the estimate.

If implementing a characteristic includes altering a specific piece of previous, brittle code that has no automated assessments in place, that threat ought to be mirrored within the estimate.


Complexity must also be thought of when offering a narrative level estimate. Assume again to the sooner instance of creating an online web page with 100 trivial textual content fields with no interactions between them.

Now take into consideration one other internet web page additionally with 100 fields. However some are date fields with calendar widgets that pop up. Some are formatted textual content fields like cellphone numbers or Social Safety numbers. Different fields do checksum validations as with bank card numbers.

This display additionally requires interactions between fields. If the consumer enters a Visa card, a three-digit CVV discipline is proven. But when the consumer enters an American Specific card, a four-digit CVV discipline is proven.

Regardless that there are nonetheless 100 fields on this display, these fields are more durable to implement. They’re extra advanced. They’ll take extra time. There’s extra probability the developer will make a mistake and be required to again up and proper it.

This extra complexity ought to be mirrored within the estimate supplied.

Think about All Elements: Quantity of Work, Threat and Uncertainty, and Complexity

It could appear unattainable to mix three elements into one quantity and supply that as an estimate to take to dash planning. It’s attainable, although, as a result of effort is the unifying issue. 
First, Scrum workforce members take into account how a lot effort shall be required to do the quantity of labor described by a product backlog merchandise.

Subsequent, these agile groups take into account how a lot effort to incorporate for coping with the danger and uncertainty inherent within the product backlog merchandise. Normally that is achieved by contemplating the danger of an issue occurring and the affect if the danger does happen. So, for instance, extra shall be included within the estimate for a time-consuming threat that’s more likely to happen than for a minor and unlikely threat.

Lastly, groups should additionally take into account the complexity of the work to be achieved. Work that’s advanced would require extra pondering, could require extra trial-and-error experimentation, maybe extra back-and-forth with a buyer, could take longer to validate and might have extra time for mistake corrections.

Throughout agile estimation, all three elements have to be mixed into one measure of effort.

Bear in mind the Definition of Finished

A narrative level estimate should embody all the pieces concerned in getting a product backlog merchandise all the way in which to achieved. If a workforce’s definition of achieved consists of creating automated assessments to validate the story (and that may be a good suggestion), the hassle to create these assessments ought to be included within the story level estimate.

Scrum, Story Factors, and Conversations

Conversations are an integral part of agile estimating. Even with thought workout routines like story factors as buckets, workforce members usually don’t agree at first on how a lot effort a narrative shall be.
These various estimates can spark illuminating conversations between workforce members and with product homeowners about acceptance standards/circumstances of satisfaction, method, and different elements that may have an effect on how a lot effort it should take to finish an merchandise. Speaking a couple of product backlog merchandise will increase the workforce’s understanding of the work, and may reveal gaps and assumptions that the product proprietor can examine.
The facility of those conversations is without doubt one of the causes I like to recommend planning poker. Planning poker is a enjoyable solution to estimate, and it’s additionally a solution to preserve every individual’s estimate personal till the workforce members all reveal their playing cards. Particular person estimates imply much less bias within the numbers and, in the end, estimates which can be extra correct.
As soon as the workforce has agreed on an estimate, it assigns story factors to the backlog merchandise. That story level estimate is later utilized in calculating a workforce’s common dash velocity, capability, and extra

Story factors could be a arduous idea to know. However the effort to totally perceive that factors characterize effort—as impacted by the quantity of labor, the complexity of the work and any threat or uncertainty within the work—shall be price it.



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