Is Function Point Analysis Valuable in an Agile Environment?

Tony MannoMany organizations are embracing Agile as their development framework of choice. The Agile project team, consisting of a Product Owner, Scrum Master and developers, creates and prioritizes user stories, which describe the functionality to be delivered by completion of the task/story. The team plans and executes in sprints to develop and implement functionality for each user story, and updates and reprioritizes the backlog of user stories (backlog grooming) for each subsequent sprint. By working in this way, Agile provides faster realization of value through incremental delivery of functionality, prioritizing the deliverables that will have the most impact. It involves the user in the development process, reduces risk by identifying issues earlier in the project lifecycle and embraces change throughout the project. It’s easy to understand why it’s become such a popular framework!

As in traditional waterfall, Agile project teams have a responsibility to the business to deliver on time and within budget. An estimate of the overall project spend and schedule can be done at the beginning of the Agile project and modified throughout the lifecycle to ensure accuracy as project requirements change. Project metrics can be derived at the end of the project and compared within the company portfolio or to industry benchmarks. But, the question is how to do this.

The answer, of course, is Function Point Analysis. Function Point Analysis is a standardized method for measuring the functionality delivered to a user, independent of technology. It works well for Agile and traditional waterfall projects. Function Point Analysis can be used at the beginning of an Agile project, once the user stories have been defined. Cost and duration estimates can be derived for the overall project from the function point counts using well defined, industry proven models and software. At the end of the project, metrics such as productivity, defect density and time-to-market are valuable in the Agile environment as within waterfall. These metrics allow measurement for internal improvement initiatives, contract compliance and comparison to industry benchmarks.

Estimation and project metrics based on functional sizing are good practices, regardless of the delivery framework used. They allow the project team to provide the business with realistic expectations of project cost and duration and to measure themselves against improvement goals and the industry.

For more insight on the use of function points in an Agile environment, check out the July 2015 DCG Trusted Advisor report, “Story Points or Function Points or Both?”


Tony Manno
Vice President, Outsourced Services

Written by Tony Manno at 09:46
Categories :

Believable Estimates

David HerronAny level-of-effort estimate for a software product, no matter how well developed, will not be 100% accurate (or at least it is very unlikely). However, that doesn't mean that the estimate shouldn't be believable.

In this case, believable means that the customer believes that the estimate is as close to accurate as possible, based on the current information, with an understanding that the outcome may change.

When an estimate is believable, it's easier to communicate with the client and to manage the project. Download my article, "Believable Estimates," to learn how to create such an estimate using Function Point Analysis.

Download


David Herron
VP, Software Performance Management

 

 

Written by David Herron at 05:00

Story Points, Function Points or Both?

Scope of this Report

Story points and function points are both methods for ‘sizing’ software. This Trusted Advisor report will establish why sizing is important and present an overview of the two sizing methods, followed by a discussion on the merits of both story points and function points by answering some very common questions:

  • Can I use function points on an Agile project?
  • Story points are much easier and faster than function points, aren't they?
  • Is there a relationship between story points and function points?

Importance of Sizing

When managing the delivery of your software product you need to know how big or small it is so you can properly plan, estimate and manage the delivery of that software. Sizing software requires a size measure that is ideally meaningful to both the development team as well as to the end user. And it should be a measure that can be applied consistently across all projects and all applications.

The development team will want to have an accurate measure of size so they can properly estimate the level of effort and duration. They will also use the size measure to monitor changing requirements (scope creep) as features or functions or stories are added to the original requirements document or product backlog. An end user or Product Owner may want a measure of size so they can understand the relative business value of what is being delivered; what features and functions the user is actually getting.

Story Points

Story points are a relative measure based on the team’s perception of the size of the work. The determination of size is based on level of understanding, how complex and how much work is required compared to other units of work. Story points are expressed according to a numerical range, which is usually constrained to a limited set of numbers such as an adaptation of a Fibonacci sequence (e.g. 1, 2, 3, 5, 8 etc.).

Story points are a relative measure used by Agile teams typically during a sprint session. Each story is assigned a story point value based on everyone’s best understanding as to the “level of difficulty” of that particular story. Of course, “level of difficulty” can include different things such as complexity,
size, duration, effort and so on. Regardless of the scale being used, in a process called planning
poker, the values assigned are assessed independently by each individual, compared by the team
and then discussed to reach a consensus. There is no consistent definition of what the values
represent other than to use it as a comparative value of one story being larger/harder or
smaller/easier than another within the one team. Over a number of iterations (sprints) an Agile team
can develop a consistent velocity (number of story points delivered per sprint) which can serve to
estimate future amounts of work/effort in future sprints. Of course, even if that one team is
achieving exactly the same volume/complexity of work as another team, their story points will not
necessarily be the same.

Function Points

“Function points measures software by quantifying the functionality requested by and provided to
the customer, based primarily on logical design”; as defined by the International Function Point
Users Group. Function points measure “software size” or, more precisely, the size
of the requirements/design specified to which the resulting software provides a “no more, no less”
solution. The size of a defined business requirement is a necessary piece of information if you want
to estimate how long it will take and how much effort it will take to develop that piece of software.
Unlike story points, function points are a defined, reproducible unit of measure. They can be
measure consistently regardless of who is measuring them. Function points can be used on both
Agile and non-Agile projects. For example, Agile user stories, for the most part, describe the features
and functions requested by the product owner.

The function point methodology calls for the identification of 5 key elements including inputs,
outputs, inquiries, interfaces and internal stores of data. Naturally there needs to be some
description of these elements; e.g., requirements documentation or stories, in order for a function
point sizing to be accomplished. Once a function point size is determined it can be used to estimate
level of effort or on the backend, the size information can be used to calculate productivity
(fp/effort hours) and quality (defects/fp) levels of performance.

Some Answers

Can I use Function Points on an Agile project?


Yes, function points can be used on an Agile project. In fact, both story points and function points
can be used on Agile projects and serve to effectively manage the project and measure
performance.

We already know that story points are used to size the user stories for a given sprint/iteration.
Stories can also be sized using function points. However, you don’t need to use function point size to
estimate how long a collection of stories in a sprint are going to take because you have already set
up a 2, 3, or 4 week cadence for your sprints.

Function Points are most useful and frequently used at the beginning of an Agile project and upon
delivery of a release or some significant delivery of functionality. In the beginning of an Agile project, you may use function points to size the entire backlog and use that size information along with additional historical data points to estimate a total project cost and a predicted delivery date. At the backend of the project you may capture total function points delivered to look at performance levels and compare Agile project performance levels to performance levels of other methodologies currently in use.

Story Points are much easier and faster than Function Points, right?

This is a true statement; story points are quicker and easier than function points. The question really becomes, which method is more appropriate for the task at hand. Sitting down with the Agile team and assigning story points to selected stories for a sprint backlog is an excellent exercise in approximating the complexity and required effort of selected stories. This is a collaborative approach that involves the team and provides a group understanding of each work element (story) and what may be involved. Even if story points were not assigned, the discussion alone would be of significant value in driving team efficiency.

Function points require a more detailed examination of the information (stories) available and achieving reproducible counts requires expertise and practice. There are specific guidelines to be applied and calculations to be made. It may be unrealistic to expect every team member of an Agile team to have this skill set. As a result, the use of function points throughout an organization is usually performed by a central specialist team thus allowing for comparisons among the various Agile teams and portfolios.

Function points are also a size measure that serves both the developer and the end user. For the developer, they are used to manage the project outcomes. For the end user (product owner) Function points can be a useful vehicle for setting expectations with regard to identifying (and agreeing) what features and functions are being developed and deployed. However, the direct involvement of the Agile team members in sizing the tasks they are going to work on has motivational benefits over the seemingly imposed sizing of the Central FP counting team.

Easier and faster are nice, but that is not the issue. The issue should be about which metric or set of metrics will provide you with the information you need to best manage the software deliverable, to make decisions and to manage expectations.

Of course, the real issue with the speed and ease of story points is that they are hard to scale across many Agile teams. For the Agile teams themselves this is not an issue but for the organization which needs to build product road maps, annual budgets, resource plans and so on, the loss of coherence is a significant one.

Is there a relationship between story points and function points?

The narrative below references the following example:

Iteration 1 – the team completed 10 stories (in a two week sprint) that were assigned a total of 50 story points. The function point size for those 10 stories was 100. The stories were focused on simple transaction I/O processing.

Iteration 2 – the team completed 5 stories in their second two week sprint. The stories were assigned 55 story points in total. The function point size for those 5 stories was 25.

Question: Assuming the team has achieved a fairly consistent velocity (50) why isn’t there a correlation between SPs and FPs?

Observations:

Story points are often assigned with some consideration of required level of effort. In the first iteration the stories involved fairly simple processing and therefore were assigned an average of 5 story points each. In the second iteration, the stories represented more complex processing and were assigned an average of 10 story points.

Function Point Analysis does not consider level of effort. It is accounting for the features and functions being delivered. The stories in iteration 1 were about processing inputs and outputs and accounted for a high number of function points. In the second iteration the stories required a greater degree of processing logic, but the features and functions being delivered were fewer.

Story Points or Function Points

Story Points are a relative measure whereas function points are a well-defined consistent method of sizing.

Does this mean that function points cannot be used to estimate at a sprint level? Sprints are time boxed, usually as two week iterations. The desired state is to achieve a steady flow of work from sprint to sprint (velocity). For Agile teams, this is adequately measured using story points. Function points are more appropriately applied to measure the overall project outcome. This can be done upon delivery of a release and/or function points can be applied when the product backlog is first developed as a means to estimate the total level of effort that may be required across all sprints.

Conclusion

Story points versus function points; so do we settle on one or the other or both? The answer is, yes.
Both these measures are useful and serve the intended purpose to more effectively manage a software deliverable.

Function points are good for measuring the overall product deliverable at the beginning and at the end. The FP size information at the beginning of a project can be used to estimate overall schedules and costs. Also, the size information upon delivery can be used to measure performance.

Story points are an effective method for managing the flow of work in an Agile project. They too serve a purpose of estimating the amount of work that can be accomplished by the team in a defined period of time (sprint/iteration).

Clearly, sometimes the best use of these two methods overlaps and so it is important to make strategic decisions about when and how they will be used rather than local, tactical decisions.

Written by Default at 05:00

How Do We Know If We Are Getting Value for Our Software Vendors?

(You can download this report here.)

Scope of this Report

Discuss what is meant by value, the process of sizing and estimating the software deliverable and the benefits of those results

  • What is “Value”?
  • Functional Value
  • More on the estimation process
  • Case study example
  • Conclusion

What is “Value”?

We can look at value for software development from vendors in terms of how much user functionality is being delivered by the software vendor. In other words, how many user features and functions are impacted as a result of a project. We can also consider whether the software deliverables were completed on time and on budget to capture “value for money” and the monetary implications of timeliness. Finally, we can see if the software project delivered what was expected from a user requirements’ perspective and if it meets the users’ needs.

This last, more subjective, assessment of value gets into issues of clarity of requirements and the difficulties of responding to emergent requirements if the initial requirements are set in stone. It is outside the scope of this report but we believe the best way to address this issue is through Agile software development which is covered in several other DCG Trusted Advisor reports.

Functional Value

To quantify the software, we must first size the project. Of course, there are several ways to do this with varying degrees of rigor and cross-project comparability. Function Points and Story Points both have sizing perspectives that take a user’s perspective of the delivered software. Since Function Points Analysis is an industry standard best practice sizing technique we find that it is used more often for sizing at this Client-Vendor interface.

Function point analysis considers the functionality that has been requested by and provided to an end
user. The functionality is categorized as pertaining to one of five key components: inputs, outputs,
inquiries, interfaces and internal data. Each of the components is evaluated and given a prescribed
weighting, resulting in a specific function point value. When complete, all functional values are added
together for a total functional size of the software deliverable. After you have established the size of the software project, the result can be used as a key input to an estimating model to help derive several other metrics that could include but are not limited to cost, delivery rate, schedule and defects. A good estimating model will include industry data that can be used to compare the resulting output metrics to benchmarks to allow the client to judge the value of the current software deliverable under
consideration. Of course, there are always mitigating circumstances but at least this approach allows for an informed value conversation (which may result in refinement of the input data to the estimating
model).

5 Key Components of Function Point Analysis

Of course, if you can base your vendor contract even partially on a cost per function point metric, this provides an excellent focus on the delivery of functional value although it is wise to have an agreed independent third party available to conduct a function point count in the event of disputes.

More on the Estimation Process

We have mentioned the importance of the estimation model and the input data in achieving a fair assessment of the functional value of the delivered software. We have also hinted that these will be issues to be discussed if there is disagreement between client and vendor about the delivered value. Hence, it is worth digging a little deeper into the estimation process.

The process for completing an estimate involves gathering key data that is related to the practices, processes and technologies used during the development lifecycle of the software deliverable. DCG analyzes the various project attributes using a commercial software tool (e.g. SEER-SEM from Galorath), assessing the expected level of effort that would be required to build the features and functions that had to be coded and tested for the software deliverable. The major areas for those technical or non-functional aspects are:

  • Platform involved (Client-server, Web based development, etc.)
  • Application Type (Financial transactions, Graphical user interface, etc.)
  • Development Method (Agile, Waterfall, etc.)
  • Current Phase (Design, Development, etc.)
  • Language (Java, C++, etc.)

Sophisticated estimating models such as those built into the commercial tools considers as well that are too numerous to mention include numerous other potential inputs including parameters are related to the personnel capabilities, develop environment and the target environment.

Given the size of the software deliverable and the complexity of the software deliverable represented by some of all of the available input parameters, we also need to know the productivity of the software development team that is developing the software. This can be a sensitive topic between Client and Vendor. We have often seen that the actual productivity of a team might be different from the reported productivity as the Vendor throws people on the team to make a delivery date (bad) or adds trainees to the team to learn (good) – mostly, for value purposes, the Client only cares about the productivity that they will be billed for!

Once we have established the development team’s rate of delivery or functions points per effort month, we can then use that information along with all the previous information (size, complexity) to deliver the completed estimate.

The end result of the sizing and estimating process would show how long the project will take to complete (Schedule), how many resources will be needed in order to complete (Effort) and the overall cost (Cost) of the software deliverable.

Sizing and Estimating Process

Case Study Example

DCG recently completed an engagement with a large global banking corporation who had an ongoing engagement with a particular vendor for various IT projects. One such project involved a migration effort to port functionality from one application platform to another new platform. The company and the vendor developed and agreed on a project timeline and associated budget. However, at the end of the allocated timeline, the vendor reported that the migration could not be completed without additional time and money.

The company was reasonably concerned about the success of the project and wanted more information as to why the vendor was unable to complete the project within the agreed-upon parameters. As a result, the company brought David Consulting Group on board to size and evaluate the work had been completed to-date, resulting in an estimation of how long that piece of work should have taken.

The objectives of the engagement were to:

  • Provide a detailed accounting of all features and functions that were included in the software being evaluated
  • Calculate the expected labor hours by activity, along with a probability report (risk analysis) for the selected releases

DCG’s initial estimate was significantly lower than what the vendor was billing for that same set of development work. With such a significant difference in the totals, it was clear that something was off. DCG investigated the issue with the vendor to explore what data could be missing from the estimate, including a review of the assumptions made in the estimate regarding:

  • Size of the job
  • Degree of complexity
  • Team’s ability to perform

In the end, the company and the vendor accepted the analysis and utilized the information internally to resolve any issues relevant to the project and as a result the company also decided to use another software vendor for any future software projects resulting in a significant cost saving.

Conclusions

This case study highlights a typical business problem wherein projects are not meeting agreed-upon parameters. In cases such as these, Function Point Analysis proves to be a useful tool in measuring and evaluating the software deliverables, providing a quantitative measure of the project being developed. The resulting function point count can also be used to track other metrics such as defects per function point, cost per function point and effort hours per function point. These metrics along with several others can be used to negotiate price points with current and future software development vendors to ensure that the company is receiving the best value for their IT investment.

The estimation process helps in keeping vendors accountable for the work they are producing by providing solid data on the realistic length of a project as well as the relative cost of the project. Quantitative estimates on project length allow companies to better manage their vendor relationships with increased oversight and an enhanced understanding of the expected outcome for their software deliverables.

Written by Default at 05:00

20 Years of IFPUG Excellence

Thank You from DCG

We're excited to extend our congratulations to the CFPS Fellows recognized today by the International Function Point Users Group (IFPUG) for 20 years of service within the software measurement community!

We thank the Fellows for their dedication to the community and to the software industry!

Read the announcement from IFPUG and see the full list of honorees here.

Written by Default at 09:31
Categories :

"It's frustrating that there are so many failed software projects when I know from personal experience that it's possible to do so much better - and we can help." 
- Mike Harris, DCG Owner

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