Estimation techniques to use in the Agile SCRUM world

2 years ago

The ART of WAG-ing

If you are not familiar with SCRUM, here is the wikipedia definition: SCRUM is an iterative, incremental framework for agile software development.

The focus of this short is the estimation aspect of a product backlog. For additional information about SCRUM, perform a Google or Youtube search. There are many sites and videos that will provide an overview in a small amount of time.

What is a WAG?

If your from the UK you might think this is an acronym for girlfriends or wife of famous football players (soccer), in software development terms however a WAG is an acronym for Wild @$$ Guess.

Estimation Techniques:

Table Top T-Shirt Sizing (S,M,L,XL)

Each backlog item is written on a 3x5 index card and placed on a table.

  • Identify the smallest sized item to act as the point of reference (S).
  • Group each card, with each corresponding group approximately twice as large as the first. (M = S+S, L = M+M)
  • Any item larger than XL is an epic which is too large to estimate.
    (These need to be re-evaluated and broken down into an estimatable size)

Table Top T-Shirt

Once all items (cards) are placed into their groups. Points are assigned to each size.

Fibonacci numbers can be used or simply double, for example:

Double: S = 1, M = 2, L = 4, XL = 8
Fibonacci: S = 1, M = 3, L = 8, XL = 13

Planning Poker

  • Each backlog item is discussed with the participating team members.
  • Each participant has a planning poker card deck.
  • Once the product backlog item has been discussed, everyone shows their card..
  • If the estimates are close together, the higher of the estimate is taken.
  • If there are large gaps between estimates then the highest and lowest discuss with each other out loud why they think their estimate is more accurate.

Planning Poker

For distributed teams, there is software available that will allow this exercise to take place. For example: PlanningPoker.com

Velocity

In physics velocity is the rate of change of position.

In Scrum, velocity is how much product backlog effort a team can handle in one sprint.

Example: Product Backlog of 1000 Points. The team has burned 300 points in three sprints. The velocity is 100 points per sprint. (300/3 = 100)

At the current velocity this team would project it would finish the remaining 700 points in 7 sprints.

See the video here on SsZ.tv.