A Fresh Look at Estimation

敏捷估算的新视角

Alan Atlas

Alan Atlas CST, CSC

Agile Conference 2012

http://www.flickr.com/photos/teuobk/2104039823/

http://www.flickr.com/photos/elenchos-seattle/3839827249/

8

“I think we will be

able to release this

feature five sprints

from now.”

“This feature will

cost two complete

sprints of our 5

person team.”

“I think we can

deliver this project

in 8 sprints.” (Actually we think 6 but we’re padding

to be careful.)

Estimation does not create value. (估算无法产生价值)

Estimation does not reduce work. (估算无法减低工作量)

Therefore, estimation is ‘waste’ in Lean terms. (因此, 从精益的角度来看, 估算是一种’浪费’)

And…

Estimates can be mistaken as commitments

(同时, 估算时常被误认为就是承诺)

To form an opinion about; evaluate. (形成一个意见; 评估)

A tentative evaluation or rough calculation, as of worth, quantity, or size. (一种暂时性的评估或者大概的有关於价值, 数量, 或者大小的计算)

A judgment based on one‘s impressions; an opinion. (根据一个人的印象所作的判断)

Usually implies a subjective and somewhat inexact judgment (通常隐含了一种主观且不怎麽準确的判断)

An oxymoron is a phrase in which

contradictory terms appear side by side.

(Oxymoron 指的是在一句话当中出现两个观念相衝突的字或词)

“It was a dark night and the moon

shone with silvery light”

Detailed Summary

Military Intelligence

American Culture

Adult Male

“I’m almost positive we are done.”

Accurate Estimate (準确的估算)

Here is a question I can answer:

How much effort can your team apply to the

project during this sprint?

Here is a question I cannot answer:

How much complexity can your team complete

during this sprint?

Here is what I do when I can’t answer a

question:

I make a guess!

24

S L

1 3 5 8 13 2

2

2

2

2

2

3

3

5

5

5

5

8

8

8

13

13

1

1

1

25

Wouldn’t it be nice if every story was the

same size?

Every story is then a ‘1’, or else a ‘247’. It

doesn’t matter.

We can do that by splitting stories until they

are all about the same size.

This gets us all of the benefits of splitting at

the same time that it eliminates estimating.

No need to estimate.

This works exceptionally well in kanban.

Story Task Pts Ideal

Hours

Consolidated

Financial Report 13

Design Integration

Data Structure

2

Import from first

data source

6

… … … …

Mike Cohn once said:

“If you are not comfortable with story

points, then just pretend one story point

equals one ideal day.”

Mike Cohn forgot to say:

“Only do that until you figure out story

points because it is not really true. It is a

trick to help you get started.”

Use ideal hours for tasks

Tasks are small and so are hours.

If you estimate effort, then story points and

ideal hours are correlated

More story points means more ideal hours

because both estimate effort

Now, since you estimate stories and tasks

differently, the two estimates can be used as

a sanity check

Story Points Sum of Task

Ideal Hours

Display Time 2 4

Enter Time

Scale

5 9

Change Time

Display

3 5

Set Y Axis Scale 1 12

Change Y Axis

Scale

3 7

Add Graph Title 3 5

Variable part timers (隨時在改變的臨時工人員數)

Specialists (專家)

Learning curve (學習曲線)

Team

Member

Percent

Allocated

Project

Hours per

day

Days

Available

this sprint

Total project

hours

available

this sprint

Xianshen 100 6 10 60

Brenda 100 6 8 48

Li 50 3 10 30

Mei 100 6 5 30

Jiang 100 6 10 60

Daniel 100 6 10 60

Total 288

Minus 10%

Scrum

Overhead 260 33

Old Days Nowadays

Always estimate

Relative estimation

using Planning Poker

Story Points and Ideal

Hours

Capacity Planning

Complexity, Effort,

and Doubt

1 Story Point = 1 Day

Estimate when

necessary

Estimate by splitting

Affinity estimation

No task estimation (or

no tasks!)

Capacity planning

when necessary