All posts by Bill Wake

Intensifying Stories Job Aid

"Intensifying stories" is an attempt to identify what can make a story (feature, capability) more potent.

I've identified key features in a number of systems (perhaps 50), identified a rule or concept beneath those features, then generalized that to apply to a number of other systems.

Intensifying Stories Job Aid (PDF)

This is no master list (nor do I expect any to exist), but I hope this list is helpful for people working to create highly-valuable capabilities in systems.

Resources on Set-Based Design

yellow woods

“Two roads diverged in a yellow wood,

yet I could travel both.”

—Not Robert Frost

 

A reading list on set-based design (part of lean product development).

 

Applied Fluid Technologies. Information on boat design.

 

Baldwin, Carliss, and Kim Clark. Design Rules, Volume 1: The Power of Modularity. MIT Press, 2000. ISBN 0262024667. Modularity and platforms, from a somewhat economic perspective; not overly focused on software modularity. (No volume 2 yet:(

 

Kennedy, Michael. Product Development for the Lean Enterprise: Why Toyota’s System is Four Times More Productive and How You Can Implement It. Oaklea Press, 2008. ISBN 1892538180. Business novel, touches on set-based approaches. 

 

Kennedy, Michael and Kent Harmon. Ready, Set, Dominate: Implement Toyota’s Set-Based Learning for Developing Products, and Nobody Can Catch You. Oaklea Press, 2008. ISBN 1892538407. Second novel, also touches on set-based approaches. 

 

Morgan, James, and Jeffrey Liker. The Toyota Product Development System. Productivity Press, 2006. ISBN 1-56327-282-2. Overview of lean product development, touches on set-based approaches. 

 

Poppendieck, Mary and Tom. "Amplify Learning." The importance of communicating constraints (rather than solutions) in set-based development. 

 

Shook, John. Managing to Learn: Using the A3 Management Process to Solve Problems, Gain Agreement, Mentor, and Lead. Lean Enterprise Institute, 2008. ISBN 1934109207. A3 reports as the heart of lean management.

 

Sobek II, Durward, Allen Ward, and Jeffrey Liker. “Toyota’s Principles of Set-Based Concurrent Engineering,” Sloan Management Review, Winter, 1998. Basic description and principles of the approach. 

 

Wake, Bill. “Set-Based Concurrent Engineering.” Overview of several variations of set-based design in software. 

 

Ward, Allen, Jeffrey Liker, John Cristiano, Durward Sobek II. “The Second Toyota Paradox: How Delaying Decisions Can Make Better Cars Faster,” Sloan Management Review, Spring, 1995. Looks at how set-based concurrent engineering lets Toyota do better than other carmakers. 

 

Ward, Allen. Lean Product and Process Development. Lean Enterprise Institute, 2007. ISBN 978-1-934109-13-7. Description of knowledge waste, set-based concurrent engineering, and a different view of the PDCA cycle.

 

This is based on a list originally prepared for Agile 2009 by Bill Wake and Jean Tabaka.

Review: In Pursuit of the Unknown (Ian Stewart)

equationsStewart

In Pursuit of the Unknown: 17 Equations That Changed the World, by Ian Stewart

Stewart explores a variety of important equations, including:

  • Pythagorean theorem,
  • the normal curve,
  • Newton's Law of Gravity,
  • Fourier transforms,
  • Black-Scholes

Each equation gets a little one-page summary, and a chapter of explanation. I can't say I could re-trace every step of the math and physics, but the explanations were interesting and intuitive enough that I didn't feel lost. These equations and their stories give you a feel for beauty in mathematics.

 

Intensifying Stories: Running with the Winners

For a given story headline, many interpretations are possible. These vary in their quality and sophistication. I call this the intensity or depth of a story. Story intensity is a knob you can control, dialing it down for earlier delivery, dialing it up for a more complex product.

For example, consider the story "System Cross-Sells Item." The simplest version could suggest the same item to everybody. The next version could have the system suggest a bestseller in the same category as a shopping-cart item. The most sophisticated version might consider past purchases from this and millions of other users, take into account the customer's wish-list, and favor high-margin items.

Lowering Intensity

The most common way to move the intensity dial is to lower intensity. This is the domain of various story-splitting strategies such as 0-1-Many or Happy Path First. These techniques are usually used to pull out the most valuable parts of a story, or to help ensure it can be implemented in a short time-frame (e.g., an iteration).

Story splitting is an important tool, but in the rest of this article we'll focus on going the other way.

Why Intensify?

The ability to intensify is valuable because we are uncertain about what is most valuable. We have hypotheses, but reality can often surprise us.

Think of it as placing bets. Suppose you have six alternatives. You can bet everything on one choice, or you can place small bets on each alternative with followup bets when you see which one is winning. Put this way, it seems clear we're better off starting with small bets, unless we're already sure about which will win.

The Lean Startup community has a related idea. They note that startups often pivot from one business model to another as they try to create a business. One pivot is called a zoom-in pivot: take a subset of the original product, and build a business on just that. An example is Flickr: it started as a game with a sharing component, but was zoomed in to focus on just the photo-sharing aspects.

Intensifying: Three Approaches

There are three common ways to intensify stories:

  1. Improve quality attributes
  2. Apply story-splitting techniques backwards
  3. Invent intensifiers that add in more options or capabilities

Improve Quality Attributes

The most straightforward way to intensify a story is to improve some quality attribute. Quality attributes, also known as non-functional requirements or "ilities," have a scale that tells how good something must be. Intensifying is just a matter of targeting a better number.

For example, suppose our system must support 125 transactions/second. We could intensify this by raising that to 500 transactions/second.

This form of intensifying is the least creative: take an attribute and ask for one 5x as good.

Be careful: some increases can be extremely expensive. A system that is 99% available can have 3.5 days of downtime per year; one with 99.9999% availability can have only ~30 seconds of downtime per year. A desktop machine might support the first one, but the second one might require a sophisticated and expensive multi-site setup.

Apply Story-Splitting in Reverse

For any story we've already split down, we can of course intensify it by combining everything back together.

But we can also use story splitting techniques as a way to generate new possibilities. For example, the 0-1-Many split says that when we have many of something, we can reduce it to 0 or 1 ways. To run this split backwards, we find something where we have only one of something, and generalize it to many.

For example, we may be able to save a document in a specific file format. We can look at this as a "one"; and look for a "many." In this case, that might mean supporting a variety of output formats.

Invent Intensifiers

The third approach is to find creative ways to improve a feature or set of features. There's no fixed set of ways to do this, though we can identify some common approaches.

Let's take a story "User finds matching item" to describe a searching process, and look at several ways to make this feature more sophisticated.

Add Control: We can provide options that let the user do a more precise or broader search:

  • Boolean operators
  • Proximity operators ("Agile within 3 words of Testing")
  • "Find more like this"

Add Intelligence: We get the system to automatically do more for us:

  • Automatically search for synonyms
  • Autofill with the most common searches
  • Automatically classify results

Manage History: Searching is rarely a one-time event; we can put the activity in more context by considering what has gone before.

  • Save searches for future use
  • Manage a list of previous searches or previous results

Manage Multiple Items: A user may have multiple searches active at once, and want to coordinate them.

  • Allow multiple search result windows
  • Compare results of two searches
  • Merge results from multiple searches

Conclusion

Intensity is a controllable characteristic of stories.

To lower intensity, standard story-splitting techniques apply.

To increase intensity, there are several approaches:

  • Improve quality attributes
  • Apply story-splitting in reverse
  • Invent intensifiers

By controlling the intensity of stories, we can better respond to the uncertainties of development and use.

Related Articles

Review: Accelerando, by Charles Stross

Accelerando Accelerando, by Charles Stross. Ace, 2006.

This novel explores the Singularity: What happens when AI, uploading, and other variations of humanity (or non-humanity) start to happen. I was worried that a novel on this subject would basically be, "Computers take over, and who knows what they're thinking?" Instead, we follow the protagonist's family through generations, and get a plausible and enjoyable flavor of what the Singularity could mean. 

Valuable Stories in the INVEST Model

Of all the attributes of the INVEST model, "Valuable" is the easiest one to, well, value. Who is against value?

We'll look at these key aspects:

  • What is value?
  • The importance of external impact
  • Value for whom?

What is Value?

Value depends on what we're trying to achieve. One old formula is IRACIS. (Gane & Sarson mentioned it in 1977 in Structured Systems Analysis, and didn't claim it was original with them.) IRACIS means:

  • Increase Revenue
  • Avoid Costs
  • Improve Service.

Increase Revenue: Add new features (or improve old ones) because somebody will pay more when they're present. 

Avoid Costs: Much software is written to help someone avoid spending money. For example, suppose you're writing software to support a call center: every second you save on a typical transaction means fewer total agents are needed, saving the company money. 

Improve Service: Some work is intended to improve existing capabilities. Consider Skype, the voice network: improving call quality is not a new feature, but it has value. (For example, more customers might stay with the service when call quality is higher.) 

IRACIS covers several types of value, but there are others:

Meet Regulations: The government may demand that we support certain capabilities (whether we want to or not). For example, credit card companies are required to support a "Do Not Call" list for customers who don't want new offers. If the company didn't provide the capability by a certain date, the government would shut down the company.

Build Reputation: Some things are done to increase our visibility in the marketplace. An example might be producing a free demo version of packaged software, to improve its marketing. In effect, these are an indirect way to increase revenue.

Create Options: Some things give us more flexibility in the future. For example, we may invest in database independence today, to give us the ability to quickly change databases in the future. The future is uncertain; options are insurance. 

Generate Information: Sometimes we need better information to help us make a good decision. For example, we might do an A-B test to tell us which color button sells more. XP-style spikes may fit this category as well.

Build Team: Sometimes a feature is chosen because it will help the team successfully bond, or learn important to the future.

Several of these values may apply at the same time. (There's nothing that makes this an exhaustive list, either.) Because multiple types of values are involved, making decisions is not easy: we have to trade across multiple dimensions. 

Valuing External Impact

Software is designed to accomplish something in the real world.

We'll lean on a classic analysis idea: describe the system's behavior as if the system is implemented with a perfect technology. Focus on the effects of the system in the world.

This helps clarify what are "real" stories: they start from outside the system and go in, or start inside and go outside. 

This also helps us avoid two problems:

  • "stories" that are about the solution we're using (the technology)
  • "stories" that are about the creators of the system, or what they want

If we frame stories so their impact is clear, product owners and users can understand what the stories bring, and make good choices about them. 

Value for Whom?

Who gets the benefit of the software we create? (One person can fill several of these roles, and this is not an exhaustive list.)

Users: The word "User" isn't the best, but we really are talking about the people who use the software. Sometimes the user may be indirect: with a call center, the agent is the direct user, and the customer talking to them is indirect. 

Purchasers: Purchasers are responsible for choosing and paying for the software. (Sometimes even these are separate roles.) Purchasers' needs often do not fully align with those of users. For example, the agents using call center software may not want to be monitored, but the purchaser of the system may require that capability.

Development Organizations: In some cases, the development organization has needs that are reflected in things like compliance to standards, use of default languages and architectures, and so on.

Sponsors: Sponsors are the people paying for the software being developed. They want some return on their investment. 

There can be other kinds of people who get value from software we develop. Part of the job of a development team is balancing the needs of various stakeholders.

Summary

We looked at what values is: IRACIS (Increase Revenue, Avoid Costs, Improve Service), as well as other things including Meeting Regulations, Generating Information, and Creating Options. 

We briefly explored the idea that good stories usually talk about what happens on the edge of the system: the effects of the software in the world.

Finally, we considered how various stakeholders benefit: users, purchasers, development organizations, and sponsors.

Value is important. It's surprisingly easy to get disconnected from it, so returning to the understanding of "What is value for this project?" is critical.

Related Material

Review: Structured Programming (Dahl, Dijkstra, and Hoare)

Structured Programming Structured Programming, by O.-J. Dahl, E.W. Dijkstra, and C.A.R. Hoare. Academic Press, 1972. 

This year (2012) is the 40th anniversary of this text, but it holds up well. It consists of three essays:

  • "Notes on Structured Programming" by E.W. Dijkstra
  • "Notes on Data Structuring" by C.A.R. Hoare
  • "Hierarchical Program Structures" by O.-J. Dahl and C.A.R. Hoare

If you've been led to think "Structured Programming = No GOTOs", the first essay will change your mind. It's much more a consideration of design in the small than a focus on surface form. 

"Data Structuring" considers how to structure types; Pascal's type structure (remember that?) of records, sets, enumerations etc. clearly embodies some of these ideas. You can see roots of the "object-based" approach (that never seemed to make it to the mainstream in the way object-oriented approaches did). 

The final essay describes mechanisms from SIMULA 67, an early (if not the original) object-oriented programming language. You can see the early consideration of objects and coroutines, classes and subclasses. 

There's definitely a "historical" air to these essays, but they hint at a path almost taken. Modern libraries and the modern rush to deliver let us ignore many ideas about software design, but they don't go away. These articles take a slower, more mathematical path than I've seen anybody apply in practice, but it brings clarity of thought about mapping problems and solutions that I'd like to imitate. 

Negotiable Stories in the INVEST Model

In the INVEST model for user stories, N is for Negotiable (and Negotiated). Negotiable hints at several important things about stories:

  • The importance of collaboration
  • Evolutionary design
  • Response to change

Collaboration

Why do firms exist? Why isn't everything done by individuals interacting in a marketplace? Nobel-prize winner Ronald Coase gave this answer: firms reduce the friction of working together. 

Working with individuals has costs: you have to find someone to work with, negotiate a contract, monitor performance carefully–and all these have a higher overhead compared to working with someone in the same firm. In effect, a company creates a zone where people can act in a higher-trust way (which often yields better results at a lower cost). 

The same dynamic, of course, plays out in software teams; teams that can act from trust and goodwill expect better results. Negotiable features take advantage of that trust: people can work together, share ideas, and jointly own the result. 

Evolutionary Design

High-level stories, written from the perspective of the actors that use the system, define capabilities of the system without over-constraining the implementation approach. This reflects a classic goal for requirements: specify what, not how. (Admittedly, the motto is better-loved than the practice.)

Consider an example: an online bookstore. (This is a company that sells stories and information printed onto pieces of paper, in a package known as a "book.") This system may have a requirement "Fulfillment sends book and receipt." At this level, we've specified our need but haven't committed to a  particular approach. Several implementations are possible:

  • A fulfillment clerk gets a note telling which items to send, picks them off the shelf, writes a receipt by hand, packages everything, and takes the accumulated packages to the delivery store every day.
  • The system generates a list of items to package, sorted by (warehouse) aisle and customer. A clerk takes this "pick list" and pushes a cart through the warehouse, picking up the items called for. A different clerk prints labels and receipts, packages the items, and leaves them where a shipper will pick them up. 
  • Items are pre-packaged and stored on smart shelves (related to the routing systems used for baggage at large airports). The shelves send the item to a labeler machine, which sends them to a sorter that crates them by zip code, for the shipper to pick up. 

Each of these approaches fulfills the requirement. (They vary in their non-functional characteristics, cost, etc.)

By keeping the story at a higher level, we leave room to negotiate: to work out a solution that takes everything into account as best we can. We can create a path that lets us evolve our solution, from basic to advanced form. 

Feedback

Waterfall development is sometimes described as "throw it over the wall": create a "perfect" description of a solution, feed it to one team for design, another for implementation, another for testing, and so on, with no real feedback between teams. But this approach assumes that you can not only correctly identify problems and solutions, but also communicate these in exactly the right way to trigger the right behavior in others. 

Some projects can work with this approach, or at least come close enough. But others are addressing "wicked problems" where any solution affects the perceived requirements in unpredictable ways. Our only hope in these situations is to intervene in some way, get feedback, and go from there.

Some teams can (or try to) create a big static backlog at the start of a project, then measure burndown until those items are all done. But this doesn't work well when feedback is needed.


Negotiable stories help even in ambiguous situations; we can work with high-level descriptions early, and build details as we go. By starting with stories at a high level, expanding details as necessary, and leaving room to adjust as we learn more, we can more easily evolve to a solution that balances all our needs.  

Related Material

The System Metaphor Explored

The System Metaphor is one of the less popular parts of Extreme Programming (XP). Newer descriptions often even omit it. But metaphor is useful – when you have  a good one, it really helps you understand and organize your system.

This post has a couple versions of a tutorial that Steve Wake and I developed and presented at some of the early Agile conferences. It's released under Creative Commons CC-BY-SA.

Versions: PPT, PDF (2-up), PDF with notes

Thee's also a SlideShare version

Independent Stories in the INVEST Model

The INVEST model is a reminder of the important characteristics of user stories, and it starts with I for Independent.

Independent stories each describe different aspects of a system's capabilities. They are easier to work with because each one can be (mostly) understood, tracked, implemented, tested, etc. on its own. 

Agile software approaches are flexible, better able to pursue whatever is most valuable today, not constrained to follow a 6-month old guess about what would be most valuable today. Independent stories help make that true: rather than a "take it or leave it" lump, they let us focus on particular aspects of a system.

We would like a system's description to be consistent and complete. Independent stories help with that too: by avoiding overlap, they reduce places where descriptions contradict each other, and they make it easier to consider whether we've described everything we need.

Three common types of dependency: overlap, order, and containment

What makes stories dependent rather than independent? There are three common types of dependency: overlap (undesirable), order (mostly can be worked around), and containment (sometimes helpful). 

Overlap Dependency

Overlap is the most painful form of dependency. Imagine a set of underlying capabilities:
        {A, B, C, D, E, F}
with stories that cover various subsets:
        {A, B}
        {A, B, F}
        {B, C, D}
        {B, C, F}
        {B, E}
        {E, F}

Quick: what's the smallest set of stories that ensure that capabilities {A, B, C, D, E, F} are present? What about {A, B, C, E}? Can we get those and nothing else?

When stories overlap, it's hard to ensure that everything is covered at least once, and we risk confusion when things are covered more than once. 

Overlapping stories create confusion.

For example, consider an email system with the stories "User sends and receives messages" and "User sends and replies to messages." (Just seeing the word "and" in a story title can make you suspicious, but you really have to consider multiple stories to know if there's overlap.) Both stories mention sending a message. We can partition the stories differently to reduce overlap:

    User sends [new] message
    User receives message
    User replies to message

(Note that we're not concerned about "technical" overlap at this level: sending and replying to messages would presumably share a lot of technical tasks. How we design the system or schedule the work is not our primary concern when we're trying to understand the system's behavior.)

Order Dependency

A second common dependency is order dependency: "this story must be implemented before that one."

Order dependencies complicate a plan,
but we can usually eliminate them.

While there's no approach that guarantees it, order dependency tends to be something that is mostly harmless and can be worked around. There are several reasons for that:

  1. Some order dependencies flow from the nature of the problem. For example, a story "User re-sends a message" naturally follows "User sends message." Even if there is an order dependency we can't eliminate, it doesn't matter since the business will tend to schedule these stories in a way that reflects it. 
  2. Even when a dependency exists, there's only a 50/50 chance we'll want to schedule things in the "wrong" order.
  3. We can find clever ways to remove most of the order dependencies.

For example, a user might need an account before they can send email. That might make us think we need to implement the account management stories first (stories like "Admin creates account"). Instead, we could build in ("hard-code") the initial accounts. (You might look at this as "hard-coding" or you might think of it as "the skinniest possible version of account management"; either way, it's a lot less work.)

Why take that approach? Because we want to explore certain areas first. We consider both value and risk. On the value side, we may focus on the parts paying customers will value most (to attract them with an early delivery). On the risk side, we may find it important to address risks, thinking of them as negative value.  In our example, we may be concerned about poor usability as a risk. A few hard-coded accounts would be enough to let us explore the usability concerns. 

Containment Dependency

Containment dependency comes in when we organize stories hierarchically: "this story contains these others." Teams use different terms for this idea: you might hear talk of "themes, epics, and stories," "features and stories," "stories and sub-stories," etc. A hierarchy is an organizational tool; it can be used formally or informally. 

A good organization for describing a system is rarely the best organization for scheduling its implementation.

The biggest caveat about a hierarchical decomposition is that while it's a helpful strategy for organizing and understanding a large set of stories, it doesn't make a good scheduling strategy. It can encourage you to do a "depth-first" schedule: address this area, and when it's done, go the next area. But really, it's unlikely that the most valuable stories will all be in a single area. Rather, we benefit from first creating a minimal version of the whole system, then a fancier version (with the next most important feature), and so on. 

Bottom Line

Independent stories help both the business and technical sides of a project. From a business perspective, the project gets a simple model focused on the business goals, not over-constrained by technical dependencies. From a technical perspective, independent stories encourage a minimal implementation, and support design approaches that minimize and mange implementation dependencies. 

Related Material

"INVEST in Good Stories, and SMART Tasks" – the original article describing the INVEST model

Composing User Stories – eLearning from Industrial Logic

User Stories Applied, by Mike Cohn

Review: Applying Domain-Driven Design and Patterns (Nilsson)

Applying Domain-Driven Design and Patterns Applying Domain-Driven Design and Patterns: With Examples in C# and .NET, by Jimmy Nilsson. Addison-Wesley, 2006.

Stir together Eric Evans' Domain-Driven Design with Martin Fowler's Patterns of Enterprise Application Architecture, mix in C# code, and you've got the flavor of this book.

It's not as classic as its antecedents. But it does provide useful examples, relating it from the perspective of someone familiar with database issues, but who now comes at things from the domain-driven perspective.

Some of the tools used have changed, but the basics still hold.

Review – Ruled Britannia (Turtledove)

Ruled Britannia

Ruled Britannia, by Harry Turtledove.

This is another of Harry Turtledove's alternative history novels. In this case, the Spanish Armada succeeded in the late 16th century, and Spain has taken over England. This is the time of Shakespeare and Queen Elizabeth, and Shakespeare ends up involved in politics and intrigue – what will become of England?

It's good fun – lots of small changes in plays and titles, and lots of witty dialog and snaps in a Shakespearean style.

The Vision Thing: How Do You Charter? #agile2011

We held a "Fringe" session at Agile 2011 to discuss how people charter or kick off projects. 

Elements of "Kickoff"

[These are in no particular order.]

  • Vision
  • Release Criteria
  • Success Criteria
  • From and To State
    • Business capability
    • Solution vision
  • Risks / Fears
  • Rallying One-Liner [may match up to Vision]
  • [Early] Backlog (maybe)
  • Mission
  • Team Agreements / Social Contract
  • Community [incl. users, customers]
  • Project Boundary
  • Domain Language
  • Scope Discussion
    • Tradeoffs
    • What's the minimum?
    • "Big rocks"
    • "Not" List
  • Guiding Principles
  • Resources / Constraints

Factors / Approaches / Techniques

  • Innovation Games
  • Metaphor
  • Mini-design studios (e.g., to explore shared understanding of "commitment")
  • Sliders
  • Ranking
  • "Not" List /  In-Out List
  • Sr. and other management present
  • No iteration 0 [get going instead]
    • -or-
  • Iteration zero that includes a skinny end-to-end "Hello World"
  • Timeboxes
  • Quickstart approach
  • Experimentation
  • Inception Deck

Thanks to all who participated!