Project Manager Success Summit - The Mythical Man-Month

Presented
with
permission
of
the
Author

By

Peter de Jager

©
2014
Peter
de
Jager

www.pmleadershipcoach.com

Published

1975

Tales
from

OS/360

Frederick
P.
Brooks
Jr.
–
Addison-‐Wesley


It
was
late

It
didn’t
meet
the
specs

It
exceeded
the
budget

It
didn’t
meet
expectations


The Man-Month is a fallacious
and dangerous Myth

...it implies that people and months
are interchangeable

Adding people
to a late
Project
makes it later…

Good cooking takes time.
If you are made to wait,
it is to serve you better,
and to please you.
Restaurant Antoine,
New Orleans

The Joy of learning
The Joy of Making things
The Pleasure of making things of value
The Fascination of making complex objects
The Delight of turning ideas into real world

One must perform
perfectly

Other people
set our objectives
The little details are just work

Debugging has a linear convergence

What you’re working on
is already obsolete

More software
projects have
gone awry for lack of calendar
time
than for all other
causes
combined.

1) We Estimate poorly
2) We Fallaciously confuse
effort with progress
3) We lack the ‘polite’
stubbornness of a Chef
4) We monitor Status poorly
5) When we fall behind,
we add more people


It takes 3 Cats…
3 Minutes…
to Catch 3 Mice
How many Cats…
Do we need to Catch
100 mice within 100 Minutes?

Which is it?
3 cats take100 Minutes...
1 Min/mouse
3 cats take102 Minutes...
3 Min/mouse
At 99 min? 99 mouses

0

20

40

60

80

100

120

1
2
3
4
5
6
7
8
9
10

Days

Workers

Non-‐Partitionable

Time


0

20

40

60

80

100

120

1
2
3
4
5
6
7
8
9
10

Days

Workers

Readily
Partitionable

Time


0

20

40

60

80

100

120

1
2
3
4
5
6
7
8
9
10

Days

Workers

Partitionable
with
Training

Time


0

20

40

60

80

100

120

1
2
3
4
5
6
7
8
9
10

Days

Workers

Partitionable
with
Training
&

Communications

Time

Comm
Effort =
n(n-1)/2

Communications Effort = n(n-1)/2

n(n-1)/2
N
Interactions

1
0


n(n-1)/2
N
Interactions

1
0

2
1


n(n-1)/2
N
Interactions

1
0

2
1

3
3


n(n-1)/2
N
Interactions

1
0

2
1

3
3

4
6


n(n-1)/2
N
Interactions

1
0

2
1

3
3

4
6

5
10


n(n-1)/2
N
Interactions

1
0

2
1

3
3

4
6

5
10

6
15

7
21

8
28

9
36

10
45


It takes time to partition a task
Time to slice it

Time to learn the slices

Time to communicate
between the slices

Regenerative Schedule Disaster
12 man-month project + 3 workers? = 4 months.

Regenerative Schedule Disaster
12 man-month project + 3 workers? = 4 months.
But… it takes 2 months to reach ﬁrst
monthly milestone… what to do?

Possible response? With 2 months calendar time
left?
-Assume estimate was sort of ‘correct’…
Of the original 12 mths? 9 months of effort
remain.
2 mths calendar left… Add 2 workers to the orig
3…

left?
- Accept that original estimate was totally wrong.
18 mths of effort 2mth calendar left – add 6
to 3

left?

Admit the promised deadline isn’t doable
Re-estimate the project based on what we know

Possible response? With 2 months left?

Trim the scope…

The solution
is in the
details of
Process

We lack the ‘polite’

stubbornness

of a Chef

We monitor Status

poorly

What we do
isn’t Simple

1) Tasks are NOT
inﬁnitely partitionable

2) People and months are NOT
interchangeable

To
Schedule
Keynotes/Workshops

contact
Peter
at:

pdejager@technobility.com

Additional
Resources:

vimeo.com/Technobility


Project Manager Success Summit - The Mythical Man-Month

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