Tag Archives: techniques

9 Agile Estimation Techniques

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Many people have used a variation of Planning Poker to do Agile estimation.  Here is a reference of 9 different Agile estimation techniques for different circumstances.  I have seen all of these techniques work in practice, except one.  Try a new one each Sprint!

Planning Poker

Participants use specially-numbered playing cards to vote for an estimate of an item.  Voting repeats with discussion until all votes are unanimous.  There are lots of minor variations on Planning Poker.  Good technique to estimate a very small number of items (2 to 10).

The Bucket System

Using the same sequence as Planning Poker, a group or a team estimate items by placing them in “buckets”.  The Bucket System is a much faster Agile estimation technique than Planning Poker because there is a “divide-and-conquer” phase.  The Bucket System can also be used with larger groups than Planning Poker and with very large numbers of items to be estimated (50 to 500).


For super-fast Agile estimation, the items to be estimated are simply placed by the group in one of three categories: big, uncertain and small.  The group starts by discussing a few together, and then, like the Bucket System, uses divide-and-conquer to go through the rest of the items.

TFB / NFC / 1 (Sprint)

This Agile estimation technique is similar to Big/Uncertain/Small but puts a specific “size” into the mix, namely 1 Sprint.  The categories are “Too F-ing Big”, “No F-ing Clue” and “1” Sprint (or less).  I learned this one recently from someone in one of my CSPO classes.

Dot Voting

Dot voting is usually considered a decision-making tool, not an Agile estimation technique.  However, for estimating small numbers of items, dot voting can be a super-simple and effective technique.  Each person gets a small number of “dots” and uses them as votes to indicate the size of an item; more dots means bigger.

T-Shirt Sizes

Items are categorized into t-shirt sizes: XS, S, M, L, XL.  The sizes can, if needed, be given numerical values after the estimation is done.  This is a very informal technique, and can be used quickly with a large number of items.  Usually, the decisions about the size are based on open, collaborative discussion, possibly with the occasional vote to break a stalemate.  There is a brief description of T-Shirt Sizes here.

Affinity Mapping

Items are grouped by similarity – where similarity is some dimension that needs to be estimated.  This is usually a very physical activity and requires a relatively small number of items (20 to 50 is a pretty good range).  The groupings are then associated with numerical estimates if desired.

Ordering Protocol

Items are placed in a random order on a scale labeled simply “low” to “high”.  Each person participating takes turns making a “move”.  A move involves one of the following actions: change the position of an item by one spot lower or one spot higher, talking about an item, or passing.  If everyone passes, the ordering is done.  The Challenge, Estimate, Override and the Relative Mass Valuation methods are variations on the ordering protocol.

Divide until Maximum Size or Less

The group decides on a maximum size for items (e.g. 1 person-day of effort).  Each item is discussed to determine if it is already that size or less.  If the item is larger than the maximum size, then the group breaks the item into sub-items and repeats the process with the sub-items.  This continues until all items are in the allowed size range.

Principles of Agile Estimation

Agile estimation techniques are collaborative.  All appropriate people are included in the process.  For example the whole Scrum team participates in estimating effort of Product Backlog Items.  Collaborative techniques are also designed so that it is impossible to blame someone for an incorrect estimate: there is no way to trace who estimated what.

Agile estimation techniques are designed to be fast (-er than traditional techniques) and deliberately trade off accuracy.  We are not trying to learn to predict the future… or get better at estimation. Instead, we recognize that estimation is a non-value added activity and minimize it as much as possible.

Most Agile estimation techniques use relative units.  This means that we don’t try to estimate dollars or days directly.  Instead, we use “points” or even qualitative labels and simply compare the items we are estimating to each other.  This takes advantage of the human capacity to compare things to each other and avoids our difficulty in comparing something to an abstract concept (such as dollars or days).

Check out my recent “Agile Planning in a Nutshell” article.

What Other Agile Estimation Methods Are There?  Please let me know in the comments and feel free to include a link!

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Collaborative Estimation Technique: Challenge, Estimate or Override (CEO)

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Great technique described by Shahin Sheidaei on his blog: Challenge, Estimate or Override (CEO) Game for Effective Estimations.  It is much quicker than the Planning Game, and probably a bit slower than the Bucket System.

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Agile Manifesto and Enterprise – Rant and Rave (Session Proposal)

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I’ve proposed a session called “Agile Manifesto and Enterprise – Rant and Rave” for the Toronto Agile Community’s conference “Toronto Agile and Software“.  The session is based loosely on my earlier article “The Agile Framework: Agile Values and Principles, The Agile Toolkit, The Agile Organization“, as well as some of the things that I do in the 2nd day of my Certified Scrum Master training session.  If you are thinking of coming to the conference, I would greatly appreciate your votes or feedback on my session proposal!

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The Three Fundamental Principles of Agile Estimation – The Third One Will Surprise You!

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You probably already use an Agile Estimation technique such as the Planning Game or the Bucket System, but surprisingly few people understand the underlying principles of Agile Estimation.  This lack of understanding often causes confusion or stress for the people who try to use Agile Estimation techniques.  The discrepancy between traditional estimation techniques and Agile techniques is large and it is hard to bridge that mental gap without understanding the principles involved.  There are three fundamental principles of Agile estimation:

Principle One: Collaborative

Agile estimation methods are collaborative.  This means that multiple people work together to arrive at estimates for work in an Agile project or product development effort.  Traditional estimation techniques (such as those related to bottom-up or top-down) tend to focus on individuals estimating the work that they are responsible for doing and “trusting” those individual estimates.  Collaborative estimation means that most estimation is done by people in formally facilitated meetings where people are present in-person.

Collaborative techniques are generally used where there is some expectation that multiple minds are better than a single mind in discovering some new knowledge or solving a problem.  Teamwork and groupwork are based on this concept.  This idea of collaboration for problem solving is also applied to Agile Estimation and it has some interesting ramifications.

The most radical consequence of collaborative estimation methods is that there is no possibility to trace a particular estimate for a particular item to a particular individual person.  This lack of traceability is important to create a sense of safety on the part of participants in the estimation effort.  This safety is necessary to allow participants to be fully honest about estimates even if those estimates conflict with expectations of powerful stakeholders.  Another way of stating this principle is that no individual can be punished for a bad estimate.

Many Agile estimation techniques take this principle beyond just mere collaboration to the level of consensus-building techniques where everyone in a group doing estimation work must agree on the final estimate for each and every item being estimated.  This strengthens the idea of safety to the point where no participant in an estimation effort can ever say “I didn’t agree with that” and thereby leave other participants “on the hook” for a bad estimate.

Principle Two: Relative Estimation

Imagine you are shown a glass bottle with some water in it.  You can see the water sloshing around.  Someone asks you, “how much water is in the bottle?”  You might, at first, think about the overall size of the bottle and respond by saying “it’s 1/3 full.”  Or, if asked to provide a measure in units like millilitres or fluid ounces, you might mentally compare what you see in front of you to some container (e.g. a measuring cup) where you know the quantity.  In both cases, you are doing a relative estimate of the amount of water in the bottle.  You are comparing the amount of water to a known quantity.

Imagine a counter-example: someone walks up to you with a red pen ask asks you “what is the wavelength of the light being reflected from this red ink?”  If you are like most people, you have probably forgotten (if you ever knew) the wavelengths of light in the visible spectrum.  You have no basis for comparison.  You might take a wild guess, but it is just that.  Going back to our relative measure, you might be able to easily say if it is darker or lighter than another red colour, or you might even be able to tell what hue of red it is.  But those cases are, again, relying on our inherent ability to see relative differences.

So instead of ignoring this capacity, in Agile estimation techniques, we leverage it.  When estimating effort, we start by setting a clear baseline for what we are comparing: another piece of work.  The baseline piece of work is often given an “estimate” that is arbitrary and in some non-standard units.  For example, it is common to use “points” when estimating the effort for Product Backlog Items.

When doing relative estimates it is very important to ensure we are comparing “apples to apples”.  Both the piece of work to be estimated and the comparison piece should both be work items that are not yet done!  If you have already completed one of the pieces of work, you have prior knowledge that you don’t have for the work to be estimated.

This last point is subtle, but important.  If you have already done something, you know much more about it.  If you try to compare to something you haven’t yet done, you will be tempted to assume that the two things will be more similar than they may be when you actually get to work on it.  By comparing two pieces of work that you have not yet done, you become much more conscious of the risks of comparing, and that consciousness will help you make better relative estimates.

It is important to note that one side advantage of using relative units for estimation is that it makes it much more difficult to use estimates as a baseline for either measuring performance or for tracking schedule variance, both of which are essentially meaningless in a good Agile environment (which should be almost entirely results-oriented).

Principle Three: Fast

In Agile estimation we don’t care (!!!) about accuracy nor about precision of estimates.  Whoa!  Why is that?  Because estimation is waste.  You can’t sell estimates, and estimates don’t affect the “form, fit or function” of the thing you’re building.  Therefore, both Agile and Lean concur: do your utmost to eliminate that waste.  There are actually lots of Agile practitioners who think estimates are evil (and they have some good arguments!)

In order to do Agile estimation in a maximally non-evil way, we need to make estimation fast!  Really fast!!!  Many of the Agile estimation techniques allow you to estimate a product release schedule lasting as much as a year in just a few hours given a reasonably well-crafted Product Backlog.

There are really only two modestly good reasons for doing estimation in an Agile project or product:

  1. Estimates provide simplified information to the Product Owner to allow him/her to make sure the Product Backlog is ready for the next Sprint (ordered, refined).
  2. Estimates allow stakeholders, including the team doing the work, to generate high-level common understanding and expectations without dwelling on details.

As a business stakeholder, one can do a simple mental exercise.  Ask yourself, “how much money would I be willing to spend to accomplish those two objectives?”  Whatever your answer, I hope that it is a very small amount compared to what you are willing to spend on getting results.  If not, perhaps you haven’t really embraced the Agile mindset yet where “the primary measure of progress is working software” (the Agile Manifesto).

Bonus Principle: We Suck at Estimating

Most people doing estimation in traditional project management try to measure in units like person-days or dollars.  There is no doubt that these units are useful if you can get good estimates.  However, most of the people doing estimation are fundamentally and irredeemably bad at it.  How do I know?  Because they are not wealthy… and have thereby proven that they cannot predict the future.  If you can predict the future, even just in limited circumstances (like estimating effort or revenue), you can leverage that to generate almost untold wealth.  Given that, it is fruitless and wasteful to try to get better at estimating.  Instead, the principles of Agile estimation help us focus our attention on the right things: collaboration, comparative estimates and doing them fast so we can get to the real work, and most importantly: delivering valuable results now.  Understanding these principles helps teams overcome many of the struggles they have in using Agile estimation techniques.

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