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Seven Diagrams Every

Software Developer

Should Understand

Also Known As

Copyright Notice

These materials are 1996-2014 Construx Software Builders,

Inc.

All Rights Reserved. No part of the contents of this seminar

may be reproduced or transmitted in any form or by any

means without the written permission of Construx Software

Builders, Inc.

Introduction

5 Construx

How Not to Be Surprised in Software Development

My Background

300 books and articles?

600 books and articles!

Another 300 books

and articles!

Another ~1000 papers,

of which only 250

were publishable

6 Construx

I did not work as hard on my next book,

Software Project Survival Guide

A History of

Attempts to Explain

Software

Development

8 Construx

A Long Line of Attempts to Explain

Software Development

http://www.computer.org/web/swebok/https://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=GLKR9ZGluCKhwM&tbnid=_6H1hCPzzz_n6M:&ved=0CAUQjRw&url=https://www.computer.org/portal/web/certification/96&ei=q7h-Uu-xKeS6iwLLqoCwBA&bvm=bv.56146854,d.cGE&psig=AFQjCNEJFhr34SQZlJuyNlQNCjZbdOP9UQ&ust=1384122921575253http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=D5aqBEUOo6xCMM&tbnid=EOSqWkQsIw3cnM:&ved=0CAUQjRw&url=http://www.canyons.org/SubTabGeneric.jsp?team=sccac&_stabid_=49518&ei=N7l-UqaIHefTiwKM8IGgCw&bvm=bv.56146854,d.cGE&psig=AFQjCNH6EQW9-xYqVkG4dMBzgmq-lVrO9A&ust=1384123058509830

9 Construx

Why do we Need to Help People

Understand Software Engineering?

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=D5aqBEUOo6xCMM&tbnid=EOSqWkQsIw3cnM:&ved=0CAUQjRw&url=http://www.canyons.org/SubTabGeneric.jsp?team=sccac&_stabid_=49518&ei=N7l-UqaIHefTiwKM8IGgCw&bvm=bv.56146854,d.cGE&psig=AFQjCNH6EQW9-xYqVkG4dMBzgmq-lVrO9A&ust=1384123058509830

10 Construx

Why do we Need to Help Other People

Understand Software Engineering? (cont.)

the pieces from several contractors had to work

have after the various parts were integrated was

difficult until the site actually went online, Bataille

about 500 million lines of software code. By

typically about one-

11 Construx

Latest Attempt to Explain Software Development

Software

Engineering

Essentials Lecture Series

CxLearn.com

12 Construx

The Goal

Help software professionals develop mental

models and frameworks to understand and

improve their software projects, to understand

the context for current software practices,

and to evaluate new developments in

software engineering .

Talk Roadmap

14 Construx

Roadmap for This Talk

Introduce four core influences

Highlight seven key diagrams

Introduce many other diagrams

that are also informative

Candidate

Top 7 Diagram

Four Core Software

Influences

16 Construx

Four Core Influences

SIZE (diseconomy of scale; failure rate ; specializations; mix of activities)

UNCERTAINTY (intellectual phases; cone of uncertainty; feature staircase vs. feature buildup; risk management; effort vs. certainty curve)

DEFECTS (DCI, defect detection lag, defect removal techniques in series, relationship to process stability)

HUMAN VARIATION (effect on research; effect on selection of methods (familiar vs. unfamiliar); effect on team composition, team

cohesion, recruiting, and retention; focus on perfect execution vs. perfect

plans; implication for favoring robust methods)

Core Influence:

Size

18 Construx

We have many informative diagrams. Which really

explains the essence of Size in Software?

Team Size

Pro

ductivity

1 ~7 ~50 ~250-350

Outp

ut

19

Diseconomy of Scale (Fred Brooks)

Efficiency is an N 2 function of the number of

people on the project due to communication

paths: N*(N -1)/2

1 person =

0 paths

2 people =

1 path

3 people =

3 paths

4 people =

6 paths

5 people =

10 paths

20

Diseconomy of Scale (Larry Putnam)

0

5

10

15

20

25

30

35

40

45

50

1.5-3 3-5 5-7 9-11 15-20

Team Size

Sch

ed

ule

(M

on

ths)

0

50

100

150

200

250

300

Eff

ort

(S

taff

Mo

nth

s)

Schedule Effort

Adapted from Lawrence H. Putnam and Ware Myers , Five Core Metrics: The Intelligence

Behind Successful Software Management

21

Efficiency is an N 2 function of the number of

people on the project due to communication

paths: N*(N -1)/2

1 person =

0 paths

2 people =

1 path

3 people =

3 paths

4 people =

6 paths

5 people =

10 paths

50 people =

1225 paths

22

Step Function

Team Size

Pro

du

ctivity

1 ~7 ~50 ~250-350

23

Diseconomy of Scale:

Step Function, Output

Team Size

Pro

du

ctivity

1 ~7 ~50 ~250-350

Outp

ut

24 Construx

Failure Rates by Size

Source: Adapted from Applied Software Measurement, 3 rd Edition (Jones 2008), Estimating Software Costs (Jones 1998).

Project Outcomes by Project Size

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

10 FP

500-1000 LOC

100 FP

5K-10K LOC

1,000 FP

50K-100K LOC

10,000 FP

500K-1M LOC

100,000 FP

5M-10M LOC

Pe

rce

nta

ge

Failed

Late

On Time

Early

25 Construx

Error Rate by Size? Productivity by Size?

-

5,000

10,000

15,000

20,000

25,000

30,000

1 KLOC 10KLOC

100KLOC

1,000KLOC

10,000KLOC

LO

C /

Sta

ff Y

ea

r

Productivity by Size

High LOC/Staff Year

Nominal

Low LOC/Staff Year

This implies that a 500 MLOC

healthcare.gov would

require at least

100,000 staff -years of effort

(all since 2010!)

-

20

40

60

80

100

120

26 Construx

Specializations by Organization Size

Cocomo Factors by

Size