Function Points and Agile

I participated in an interesting conversation on Function Points and Agile with members of the software development group at a federal agency recently.  We, the DCG team, were explaining how we would start the process of measuring how much value they are delivering from software development by measuring how much functionality they are delivering in function points.  For an organization with immature metrics and, perhaps, lack of user trust, this starting point takes the question of productivity off of the table to allow us to move on to end user value delivery

All of the participants in the meeting quickly recognized the value of having a standard metric, function points, to measure the size of the functionality being delivered (and with SNAP – the non-functional size too) but I could see on their faces the sort of trusting disbelief that might be associated with my pulling a rabbit out of my bag.   Some of the participants in the meeting were not familiar with function points and asked for a quick, five minute explanation.  I get asked this a lot so here it is (before I get inundated with corrections – I know - this is an over-simplification):

Imagine a software application and draw an imaginary boundary around it in your mind to include all its functionality but not the functionality of other applications that it communicates with or draws information from.  Now consider the diagram below.

Function Points and Agile

From a user perspective, looking at the application from outside the application boundary, I can interact with the application in three ways, called transaction functions: external inputs (EIs), external outputs (Eos) and external inquiries (same as input and output but with no change of data or state - EQs).  From within the application, I can access data in two places – inside the application boundary or outside the application boundary.  My interactions with these files are the two types of data functions: internal logical files (ILFs) where data is stored within the application boundary and external interface files (EIFs) where data is stored outside our application boundary. 

Most of you will be able to easily imagine that these five types of user interaction with our application can be more or less complex.  If I want to produce a function point count, the next step is to consider the first of the transactions that the user wishes to perform on the application (as defined in the requirements, user stories or whatever) and to identify how many of each of the five function types is involved in the transaction and how complex that involvement is (low, average or high).  Predetermined rules govern the weights that apply to each function type based on the complexity of the function in this transaction.  With all this information gathered, we can calculate the number of function points using the simple table shown below.

Function Point Counting Weights









__ x 3 +

__ x 4 +

__ x 6 =




__ x 4 +

__ x 5 +

__ x 7 =




__ x 3 +

__ x 4 +

__ x 6 =




__ x 7 +

__ x10 +

__ x15 =




__ x 5 +

__ x 7 +

__ x10 =









One of the participants offered a very perceptive observation, “Isn’t this a lot of work for every user story in Agile?”  It could be.  In practice though, by the time a user story is defined and understood, the software problem has been decomposed to the point where identifying the FPA functions and complexities is fairly simple.  That said, we don’t recommend this for all agile team members.  Story points work fine for most agile teams.  Where function points (and SNAP) can and must be used for Agile is where there is a need to aggregate the delivered functionality (and non-functional elements) into higher level metrics  for reporting to management.  This level of function point analysis is often better done by a separate, central team rather than the agile team members themselves.


Written by Michael D. Harris at 15:17
Categories :

How to Count Function Points from User Stories

I was recently involved in a consulting engagement where Agile methodologies were being implemented with User Stories as the documentation standard. The organization had used function points (FPs) for years on their waterfall projects and were wondering if they could use them for their Agile methodology – and if User Stories would be a good input into the FP counting process. The answer I provided was a resounding “YES.” Having User Stories is actually a huge advantage to counting FPs, especially early in the lifecycle, because User Stories are typically focused on the user perspective, just like FPs.

The only difficulty in using FPs in Agile methodologies is determining what to count and when to count. As with any metric, this always goes back to the purpose. For example, if you want to know the size of the final delivered product, then you count the FPs at the end of the project. If you want to estimate effort for a Sprint or Program Increment (PI), then you need to count at the beginning of the Sprint or PI.  The key is defining the purpose early in order to have access to what you need at the time of data collection.

When actually counting FPs from User Stories, there are a few tips that help with the process. Depending on the level of the User Stories, more questions or assumptions may be needed to get to an accurate FP count. There are also key words used in User Stories that may help identify FP components (e.g. Maintain, Report, Enter, Select). Often User Stories equate to transactional functions in FPs, so it is important for the FP analyst to identify data functions as they go along.

More tips and advice, including real-life examples, will be provided in my upcoming webinar, “Counting Function Points from User Stories,” taking place on Wednesday September 28, 2016 at 12:00 pm EST. Please register here. If you have any questions before the webinar, just leave a comment and I’ll be sure to address them during the presentation.

Lori Limbacher
Estimation Specialist; Certified Function Point Specialist (CFPS)

Written by Lori Limbacher at 05:00
Categories :

Function Points in the Philippines?

David LambertI know what you are thinking – and I was thinking the same thing. Is there really a company using function points in the Philippines? Yes, there is. In fact, I recently traveled to the Philippines to train a lean development team on the use of function points as a measure for their metrics program.

I’d never been to the Philippines before, so it was an interesting experience to be in a new place, but it was also interesting to see how function points are being used around the world.

This particular team is way above the curve as far as their processes and documentation is concerned. They were looking for a standardized process to size their change requests in order to measure productivity and quality and help forecast future projects. Their intent is to start sizing those small change requests and establish some benchmarks for their applications. Once those benchmarks are in place and they have gathered some valuable data, the team intends to start using the data to help size their larger projects. The sizing for those projects will allow them to better manage staffing, cost, and quality related to those projects.

This, of course, is something we encourage and espouse as a best practice for development teams. So, it was great to see that this mentality has really taken hold in this organization, and that they truly understand the benefits of sizing.

I also learned while I was there that several larger technology companies are starting to use the Philippines as a source to locate their infrastructure and development teams. So you may not think of the Philippines when it comes to the IT domain, but the country is starting to make some strides towards closing the gap on the rest of IT world. I know for sure that one lean development team has closed the gap and function points have allowed them to standardize their process even further.

I look forward to seeing how the use of function points continues to develop in the country – and beyond. Is your organization using function points? If not, it’s time to catch up!


David Lambert
Managing Consultant

Written by David Lambert at 05:00

IT Project Failures

Mike HarrisFailures in IT never seem to go away. Every month the news seems to be covering a new, high-profile IT issue, many of which Jay Liebowitz enumerates in his recent IT Professional article, “IT Project Failures: What Management Can Learn.”, The National Program for IT (UK), United Airlines, the Wall Street Journal, and even the New York Stock Exchange have all experienced very public, very high-profile failures. Why?

As Liebowitz notes, many organizations blame these failures on scope, cost, and time, but they can be further categorized by process-driven, context-driven, and content-driven issues.

  • Process-driven: Those related to business planning, project management and control, strategic formulation, and the change-management process.
  • Context-driven: Those related to the information system itself (technology, system design).
  • Content-driven: Those related to the environment in which the project is being development (culture, structure, management).

One process-driven issue that is often the impetus for failure is when organizations pick the project they like the best – without taking into account the business case for that project. If you’ve been in IT long enough, you’ve seen this happen. Needless failure.

Liebowitz also points to research from Rateb Swies asserting that IT projects fail due to the following reasons (in priority order):

  1. High degree of customization (context-driven)
  2. Changes late in the design stage (process-driven)
  3. Underestimating the timeline (process-driven)

So the question, of course, is what can management do? An obvious solution, suggested by Liebowitz, is to better educate current and future IT project leaders. Specifically, I recommend the following:

  1. High degree of customization (context-driven) – Management needs to better understand the size of the project. Function points can help.
  2. Changes late in the design stage (process-driven) – Management needs to understand the impact of these changes. Better IT governance can help.
  3. Underestimating the timeline (process-driven) – Management needs to understand the probability of the estimates that they are getting. Better estimating using statistical analysis and, yes, a tool can help.

Liebowitz also suggests better coordination between business users, IT, and finance. I’ve talked about this on the blog repeatedly – the need for improved coordination between IT and the business is paramount.

We have a number of services that support this type of improvement, including Function Point Analysis, IT Governance, and the Measurement Roadmap. IT serves to support the goals of the business; if it’s not appropriately aligned with the interests of the business, then it’s not fulfilling its role and failure will be more likely.

Management has the ability and the tools available to prevent failure – so when will they start doing their part?

Read, “IT Project Failures,” here.

Mike Harris



Written by Michael D. Harris at 05:00

The Origins of Function Point Measures

Trusted Advisor

Note of Thanks

We’re pleased to share this month’s Trusted Advisor, which was written by Capers Jones. Capers is a well-known author and speaker on topics related to software estimation. He is the co-founder, Vice President, and Chief Technology Officer of Namcook Analytics LLC, which builds patent-pending advanced risk, quality, and cost estimation tools. Many thanks to Capers for participating in Trusted Advisor and allowing us to publish his report!

Scope of Report

The 30th anniversary of the International Function Point User’s Group (IFPUG) is approaching. As such, this report addresses a brief history of the origin of function points. The author, Capers Jones, was working at IBM in the 1960’s and 1970’s, observing the origins of several IBM technologies, such as inspections, parametric estimation tools, and function point metrics. This report discusses the origins and evolution of function point metrics.


In the 1960’s and 1970’s IBM was developing new programming languages, such as APL, PL/I, PL/S etc. IBM executives wanted to attract customers to these new languages by showing clients higher productivity rates. As it happens, the compilers for various languages were identical in scope and had the same features. Some older compilers were coded in assembly language, while newer compilers were coded in PL/S, which was a new IBM language for systems software. When we measured productivity of assembly-language compilers versus PL/S compilers using “lines of code (LOC),” we found that even though PL/S took less effort, LOC per month favored assembly language. This problem is easiest to see when comparing products that are almost identical but merely coded in different languages. Compilers, of course, are very similar. Other products, besides compilers, that are close enough in feature sets to have their productivity negatively impacted by LOC metrics are PBX switches, ATM banking controls, insurance claims handling, and sorts.

A Better Metric

To show the value of higher-level languages, the first IBM approach was to convert high-level languages into “equivalent assembly language.” In other words, we measured productivity against a synthetic size based on assembly language instead of against true LOC size in the actual higher level languages. This method was used by IBM from around 1968 through 1972.

An IBM Vice President, Ted Climis, said that IBM was investing a lot of money into new and better programming languages. Neither he nor clients could understand why we had to use the old assembly language as the metric to show productivity gains for new languages. This was counter-productive to the IBM strategy of moving customers to better programming languages. He wanted a better metric that was language independent and could be used to show the value of all IBM high-level languages. This led to the IBM investment in function point metrics and to the creation of a function-point development team under Al Albrecht at IBM White Plains. 

The Origin of Function Points

Function point metrics were developed by the IBM team by around 1975 and used internally and successfully. In 1978, IBM placed function point metrics in the public domain and announced them via a technical paper given by Al Albrecht at a joint IBM/SHARE/Guide conference in Monterey, California. Table 1 shows the underlying reason for the IBM function point invention based on the early comparison of assembly language and PL/S for IBM compilers. Table 1 shows productivity in four separate flavors:

1. Actual lines of code in the true languages.
2. Productivity based on “equivalent assembly code.”
3. Productivity based on “function points per month.”
4. Productivity based on “work hours per function point.”

Function Point Evolution

The creation and evolution of function point metrics was based on a need to show IBM clients the value of IBM’s emerging family of high-level programming languages, such as PL/I, APL, and others. This is still a valuable use of function points, since there are more than 2,500 programming languages in 2016 and new languages are being created at a rate of more than one per month.

Another advantage of function point metrics vis a vis LOC metrics is that function points can measure the productivity of non-coding tasks, such as creation of requirements and design documents. In fact, function points can measure all software activities, while LOC can only measure coding.

Up until the explosion of higher-level programming languages occurred, assembly language was the only language used for systems software (the author programmed in assembly for several years when starting out as a young programmer).

With only one programming language, LOC metrics worked reasonably well. It was only when higher-level programming languages appeared that the LOC problems became apparent. It was soon realized that the essential problem with the LOC metric is really nothing more than a basic issue of manufacturing economics that had been understood by other industries for over 200 years.

This is a fundamental law of manufacturing economics: “When a manufacturing process has a high percentage of fixed costs and there is a decline in the number of units produced, the cost per unit will go up.”

The software non-coding work of requirements, design, and documentation acts like fixed costs. When there is a move from a low-level language, such as assembly, to a higher-level language, such as PL/S, the cost-per-unit will go up, assuming that LOC is the “unit” selected for measuring the product. This is because of the fixed costs of the non-code work and the reduction of code “units” for higher-level programming languages.

Function point metrics are not based on code at all, but are an abstract metric that defines the essence of the features that the software provides to users. This means that applications with the same feature sets will be the same size in terms of function points no matter what languages they are coded in. Productivity and quality can go up and down, of course, but they change in response to team skills.

The Expansion of Function Points

Function points were released by IBM in 1978 and other companies began to use them, and soon the International Function Point User’s Group (IFPUG) was formed in Canada.

Today, in 2016, there are hundreds of thousands of function point users and hundreds of thousands of benchmarks based on function points. There are also several other varieties of function points, such as COSMIC, FISMA, NESMA, etc.

Overall, function points have proven to be a successful metric and are now widely used for productivity studies, quality studies, and economic analysis of software trends. Function point metrics are supported by parametric estimation tools and also by benchmark studies. There are several flavors of automatic function point tools. There are function point associations in most industrialized countries. There are also ISO standards for functional size measurement.

(There was never an ISO standard for code counting, and counting methods vary widely from company to company and project to project. In a benchmark study performed for a “LOC” shop, we found four sets of counting rules for LOC that varied by over 500%).

Table 2 shows countries with increasing function point usage circa 2016, and it also shows the countries where function point metrics are now required for government software projects.

Expanding Use of Function Points

Several other countries will probably also mandate function points for government software contracts by 2017. Eventually most countries will do this. In retrospect, function point metrics have proven to be a powerful tool for software economic and quality analysis.

Trusted Advisor Guest Author

Again, our sincere thanks are extended to our guest author, Capers Jones.

You can download this report here

Written by Default at 05:00

"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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