Planning Poker - Agile Estimation

A consensus based estimation technique mainly used in agile environment. It can be used to estimate days or story points for any requirement.

Equipment needed:

• A deck of cards: Cards in the deck have numbers on them. A typical deck has cards showing the Fibonacci sequence including a zero: 0, 1, 2, 3, 5, 8, 13, 21, 34, 55, and 89.
• Requirement list (which need to be estimated

How to apply:

• A Moderator, who normally doesn’t play, chairs the meeting.
• The Product Owner provides a short overview of the user story. The team is given an opportunity to ask questions and discuss to clarify assumptions and risks.
• Each individual lays a card face down representing his/her estimate instead of speaking them aloud.
• Everyone calls their cards simultaneously by turning them over.
• People with high estimates and low estimates has given the opportunity to justify their estimate and then discussion continues.
• This estimation process is repeated until a consensus is reached for a particular feature and then it is repeated for next requirement item

Pert - A Three Point Estimation Technique

The PERT Three Point Estimate technique is a type of three point estimate. It can be applied to cost and duration.  The only difference between pert and three point estimation is that it applies weighting so that the most-likely estimate is weighted 4 times more than the other two estimates (optimistic and pessimistic). 

When to use:        

For projects which are unique, such as R&D projects where there are many unknowns. 

Estimate:

E (Pert) = (O + 4M + P) / 6

E (Three Point Estimation) = (O + M + P) / 3

E is Total Estimate

O = optimistic estimate

P = pessimistic estimate

M = most likely estimate

Standard Deviation

SD (Pert) = (P − O)/6

SD is Standard Deviation

Steps to produce PERT estimate:

• Decompose the project into a list of estimable tasks, i.e. identify tasks for each Work Breakdown Structure (WBS) work package
• Estimate E and SD for each task.
• Calculate E for the total project work as E (Project Work) = Σ E
• Calculate SD value for the total project work as SD (Project Work) = √Σ SD

Now E and SD values are used to get the confidence levels as follows:

• Confidence level in E value +/- SD is approximately 68%
• Confidence level in E value +/- 1.645 × SD is approximately 90%
• Confidence level in E value +/- 2 × SD is approximately 95%
• Confidence level in E value +/- 3 × SD is approximately 99.7%

Information Systems typically use the 95% confidence level, i.e. E Value + 1.645 × SD, for all project and task estimates