Effort estimation in agile projects Elad Sofer - Agile coach & Scrum master. Nokia Siemens networks blog - http://eladsof.blogli.co.il LinkedIn - http://www.linkedin.com/in/eladsofer

How to estimate this task ?

What makes estimation agile ? Effort estimation Is not considered as a phase in the project Changes are expected, embrace change. Estimations are easily correctable. Estimate by feature not by activity Estimate by a multi-disciplinary team. And…

Effort estimation Is not considered as a phase in the project

Changes are expected, embrace change.

Estimations are easily correctable.

Estimate by feature not by activity

Estimate by a multi-disciplinary team.

And…

“ It’s better to be roughly right than precisely wrong.” [John Maynard Keynes [

Persistence of time

How long will it take to… Read the bible Drive to Paris ? Solve a math equation ? Add support for LDAP ?

Read the bible

Drive to Paris ?

Solve a math equation ?

Add support for LDAP ?

34.4

Basic assumptions for estimation We are not good in measuring absolute values. We are good in comparing things. We have the basic math skills (or a calculator). High accuracy has a high toll. Estimates are not commitments Time is not persistent.

We are not good in measuring absolute values.

We are good in comparing things.

We have the basic math skills (or a calculator).

High accuracy has a high toll.

Estimates are not commitments

Time is not persistent.

Story points Unitless. Name is derived from user stories. They reflect the “bigness” of a user story. How hard it is ? How risky it is ? How much of it there is ? Relative values matters. Point values “include uncertainty”. Easy and quick A little effort helps a lot A lot of effort helps a little more

Unitless.

Name is derived from user stories.

They reflect the “bigness” of a user story.

How hard it is ?

How risky it is ?

How much of it there is ?

Relative values matters.

Point values “include uncertainty”.

Easy and quick

A little effort helps a lot

A lot of effort helps a little more

Estimation techniques Expert opinion Analogy Educated guess Disaggregating Planning poker

Expert opinion

Analogy

Educated guess

Disaggregating

Planning poker

Planning poker Each person gets a deck of cards. The item to be estimated is read to all. Attendants ask clarifications for the item. Each person selects a card and puts it on the table facing down. When everyone is done, cards are exposed. If the estimations do not match a short discussion is done. -> Goto 4. Handle next item.

Each person gets a deck of cards.

The item to be estimated is read to all.

Attendants ask clarifications for the item.

Each person selects a card and puts it on the table facing down.

When everyone is done, cards are exposed.

If the estimations do not match a short discussion is done. -> Goto 4.

Handle next item.

Why planning poker works ? Those who do the work estimate it. Emphasizes relative estimation Estimates are within one order of magnitude. Reduces anchoring - Everyone's opinion is heard.

Those who do the work estimate it.

Emphasizes relative estimation

Estimates are within one order of magnitude.

Reduces anchoring - Everyone's opinion is heard.

Specification length One page spec Group A 7 Pages spec Group B 173 hours 117 hours

One page spec

Group A

7 Pages spec

Group B

Irrelevant information Group A added irrelevant details: End user desktop apps Usernames & passwords Etc. Group B 39 hours 20 hours

Group A

added irrelevant details:

End user desktop apps

Usernames & passwords

Etc.

Group B

Extra requirements Requirements 1-4 Group A Requirements 1-5 Group B 4 hours 4 hours Requirements 1-5 but told to estimate 1-4 only Group C 8 hours

Requirements 1-4

Group A

Requirements 1-5

Group B

Requirements 1-5 but told to estimate 1-4 only

Group C

Given anchor Group A Customer thinks 500 customer has no technical knowledge Don’t let the customer influence you Group B 555 hours 456 hours Same as B customer thinks 50 Group C 99 hours

Group A

Customer thinks 500

customer has no technical knowledge

Don’t let the customer influence you

Group B

Same as B customer thinks 50

Group C

Why planning poker works ? Those who do the work estimate it. Emphasizes relative estimation Estimates are within one order of magnitude. Reduces anchoring - Everyone's opinion is heard. Modeled for open discussion – forces thinking. It’s quick & fun !

Those who do the work estimate it.

Emphasizes relative estimation

Estimates are within one order of magnitude.

Reduces anchoring - Everyone's opinion is heard.

Modeled for open discussion – forces thinking.

It’s quick & fun !

How to calculate time ? S V T

Velocity How many points can the team complete in one iteration. Easy to measure. Fixes estimation errors. Easily reflects the project status. Primary parameter in planning.

How many points can the team complete in one iteration.

Easy to measure.

Fixes estimation errors.

Easily reflects the project status.

Primary parameter in planning.

vs + So what will it be ?