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January 22, 2013 / KaTe

A guide to Estimation Card Games like Planning Poker

*Remember that this has been written as a paper. So formal language is unfortunately necessary*

Overview

When estimating as a group, the team tends to be more accurate than an individual. The phenomenon known as the Wisdom Of The Crowd[1] is a renowned effect widely used in multiple industries. This effect is especially strong when dealing with estimation of size[2].

Everyone working with a Scrum Team can benefit from using the Planning Card Game. Main applications are estimating size and value of Product Backlog Items, but are not limited to them.  Teams estimating benefit in exchanging knowledge and the Product Owner benefits from values produced while playing.

Starting Conditions

Choosing estimation units

Before the estimation can begin, the estimating group has to choose their estimation unit. Units can be divided into two main groups – absolute and relative.

Absolute

It is possible to use the Planning Card Game using absolute units, but it has been observed that those units tend to turn into relative ones creating confusion of what they actually stand for (the Relativity Effect described below).

Humans in general tend to underestimate work when asked for an absolute value, for example hours[3] or currency.  Also if using those, the work has to be re-estimated often as the team learns new things and can complete tasks in shorter time period. This time is actually wasted.

Relative

Relative estimation units are more natural. The chain of thought of human brain, even if estimating in absolute units, contains relative estimation implicitly. When asked to give hourly estimate, we first try to find something similar that we completed and then give the relative value.

Using relative units, like Story points we have to remember that they vary from team to team and are not comparable between them. They require a probation period, usually in the form of the first (or few) Sprint before they can be used for costing and future projections with reasonable error margin.

The process of estimation in form of the Planning Card Game takes a higher amount of man hours compared to estimates delivered by a single specialist, but it’s given in shorter time period and tends to be significantly more accurate.

If the team acquires a new skill and they are able to complete requirements in shorter time there is no need for re-estimation. Units are still relative to each other and it will be reflected in greater velocity.

Choosing or composing a deckplanning poker cards

To begin playing The Planning Card Game it is essential to create a deck that would address possible dysfunctions and reinforce desired behaviors. For example, adding a ½ card in a deck used by a team with lots of people with attention to detail might lead into endless discussions whether an item should be a ½ or a 1. On the other hand if the team prefers to break items into very small pieces a ½ can be a desired figure.

Fibonacci Sequence and variations

The basic deck for the planning game consists of: 1,2,3,5,8 and 13. Some teams decide on extending it up by 20, 21, 35, 40, 44, 60 and so on.

Very large and infinity cards

Most commercial decks contain values up to ~40 and then a card marked  as an infinity or a “BIG” which means that the item is too big to estimate  it with a reasonable probability.

Half and Zero

Some decks contain “0”, which is used to mark that there is no work needed to perform to add this functionality. Usually it was done accidentally or is included in another item.  Another value in the deck is a ½ – it’s used exactly like other numerical values.

Coffee

It’s mainly used when playing long games (for example initial estimations of the whole project). Coffee indicates a need for a break.

Question Mark

Another variation is a question mark, which is widely used, especially with teams that grow, change members often, or where skill sets are very distinctive. It’s used to indicate “I have no idea how big this item might be”.  When having this card in the deck, game does not stop even when someone does not know anything about the subject. It also reduces the “safe five effect” This card is especially useful for increasing cross-functionality for the team. The person using it acts as a probe for people knowing the subject more. If they are able to understand and estimate the item, it has been clearly described and doubts have been removed.

Bomb

This card can be inserted instead of the infinity. It states that the item is either too big, too complex or needs to be broken down or investigated in order to proceed.

Other decks

There are also decks that consist of T-Shirt sizes (… XS, S, M, L, XL …), are the powers of two or basic numbers. Teams can also use classic playing cards.

Example numerical decks:

0, ½ , 1, 2, 3, 5, 8, 13, 20, 40, 60, 100, ?, ∞

0, 1, 2, 3, 5, 8, 13, 21, 44, ?, ∞

1, 2, 3, 5, 8, 13, 21, 100, ?, Coffee

Playing the game

Process

The process is simple.

  1. The Product Backlog item to be estimated is presented and explained roughly.
  2. Each estimator places one card out of his/her hand face down on the table.
  3. When everyone has a card on the table, they are all flipped at once.
  4. If all of the cards are identical, the estimate is valid. If there are differences, person with the highest and lowest number explains why did he/she choose this estimate.
  5. After explanations there is another round. Again the highest and lowest estimate should be explained, but the moderator should concentrate on people that changed their estimate and investigate why.
  6. Continue rounds until all estimates are the same. Value might be modified when item is already completed.

Safe Five Effect

The Safe Five Effect – it’s an effect that exhibits itself with a huge amount of fives in the estimated list. It can be caused by the fact that some team members are unfamiliar with either the domain or technology and they play a five each time to minimize the probability of being far off from other team members’ estimates.

Deadlock

If there are two adjacent numbers being shown for two or more rounds, for example a five and an eight, the team should accept a higher estimate. This is a safer way – in case the negative scenario happens, the estimate is correct.

Anchoring

In the process of playing it is forbidden to give hints on the size before the first round of estimates is revealed. If someone says “it’s easy”, especially a technical expert, whole team’s perception of the subject will then be shifted towards the suggestion and the valuable discussion will not occur.

Relativity Effect

When the Planning Card Game is used with absolute units, they can turn relative after some time. It can be spotted by the fact that the team burns more hours or man-days in a sprint than there is physically available. This effect is not necessarily negative, but it is recommended that if it occurs, the name of the unit to be changed.

Result

The game usually results in adding details to estimated items and changing some of them as more is uncovered in the discussion. It might also result in questions that have not been asked during the initial specification of items.

Intended Outcome

The Planning Card Game brings value to the Product Owner in form of the basis for further planning and costing.

The value to the Development Team is different. Although being aware of their velocity can be beneficial, the real power lays with the process of playing. While explaining estimates, the team experiences knowledge transfer among people with different skill sets. In addition some Product Backlog Items are clarified further, or lack of certain information is exposed, so that they can be provided later. The process also uncovers new aspects to requirements, so they have to be constantly clarified with the customer.

The value for the stakeholders corresponds to the value for the Product Owner. They are better informed on the progress of work, so that they can make conscious business decisions. True state of the product is revealed and stakeholders depending on it can adjust their plans accordingly.

Top-down Planning Game

There is a modification of the Planning Game for top-down estimates. It requires relative units.  A team might decide to use a bigger unit for bigger items or groups of them. This unit should be named differently than the smaller one.  A team can work on items already completed, to determine the scale. Then when a new set of items arrive, the team can use the process to estimate top-down


[1]  Surowiecki, J. (2004). The wisdom of crowds. New York: Random House.

[2] Vul, E & Pashler, H (2008) “Measuring the Crowd Within: Probabilistic representations Within individuals” Psychological Science. 19(7) 645-647.

[3] Buehler, R., Griffin, D., & Ross, M. (1994). Exploring the “planning fallacy”: Why people underestimate their task completion times. Journal of Personality and Social Psychology, 67(3), 366-381.

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