Download Pair Programming: Why Have Two Do the Work of One?

A Tale of Two XP Teams
“It was the best of times, it was the worst of times.”
Laurie Williams
North Carolina State University
Agenda

IBM Team: “Safe Subset” of XP Practices

Sabre Airline Solutions Team: “Mostly all” of XP

Summary/Comparison
Extreme Programming Examination
Extreme Programming Evaluation Framework
XP-EF (said X-pef)
XP-Context
Factors (XP-cf)
XP-Adherence
Metrics (XP-am)
(said X-pam)
XP-Outcome
Measures (XP-om)
(said X-pom)
•Reusable framework for reporting:
•the extent to which an organization has adopted XP practices;
and
•the result of this adoption
IBM: XP-Context Factors (XP-cf)





Small team (7-10)
Co-located
Web development (toolkit)
Supplier and customer
distributed (US and
overseas)
Examined one release
“old” (low XP) to the next
“new” (more XP)
IBM: XP-Adherence Metrics (XP-am)

Subjective: Shodan Survey (http://agile.csc.ncsu.edu/survey)
–
–

Old 56%
New 72%
Objective Metrics
XP-am Metric
Practice
Old
New
Automated test class per user
story
Testing
0.11
0.45
Test coverage (statement)
Testing
30%
46%
Unit test runs per person day
Testing
14%
11%
Test LOC/Srce LOC
Testing
0.26
0.42
Accept test execute
Testing
Manual
Manual
Did customers run your
acceptance tests?
Testing
No
No
Pairing Frequency
Pair Pro
<5%
48%
Release Length
Shrt Rel
10 months
5 months
Iteration Length
Shrt Rel
Weekly
Weekly
IBM: XP-Outcome Measures (XP-om)
XP Result Metric
Old
New
Internal Code Structure (mean values)
Methods per class
Depth of inheritance tree
Number of children
Coupling
Response for class
Lines of code per class
McCabe Complexity
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.96
0.96
1.55
1.01
0.99
0.98
0.74
Response to Customer Change
(Ratio (user stories in + out) /total)
NA
0.23
Internally-Visible Quality
(test defects/KLOEC of code)
1.0
0.50
Externally-Visible Quality
(released defects/KLOEC of code)
1.0
0.24
Productivity (stories / PM)
Relative KLOEC / PM
1.0
1.0
1.34
1.7
Customer Satisfaction
NA
High
Morale (via survey)
1.0
1.11
Sabre: XP-Context Factors (XP-cf)





Small team (6-10)
Co-located
Scriptable GUI
environment
Customer remote,
multinational, several time
zones
Examined third release
“old” (low XP) to the ninth
release “new” (sustained
XP)
Sabre: XP-Adherence Metrics (XP-am)

Subjective: Shodan Survey
–

New 77%
Objective Metrics
XP-am Metric
Practice
Old
New
Automated test class per user
story
Testing
N/A
3.22
Test coverage (statement)
Testing
N/A
32.9%
Unit test runs per person day
Testing
None
1.0 (anecdotal)
Test LOC/Srce LOC
Testing
0.054
0.296
Accept test execute
Testing
Manual
Manual
Did customers run your
acceptance tests?
Testing
No
No
Pairing Frequency
Pair Pro
0%
50%
Release Length
Shrt Rel
18 months
3.5 months
Iteration Length
Shrt Rel
None
10 days
Sabre: XP-Outcome Measures (XP-om)
XP Result Metric
Old
New
Internal Code Structure (mean values)
Methods per class
Depth of inheritance tree
Number of children
Coupling
Response for class
Lines of code per class
McCabe Complexity
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.50
1.00
1.00
1.17
1.28
1.15
1.35
Response to Customer Change
(Ratio (user stories in + out) /total)
NA
N/A
Internally-Visible Quality
(test defects/KLOEC of code)
1.0
0.25
Externally-Visible Quality
(released defects/KLOEC of code)
1.0
0.70
Productivity (stories / PM)
Relative KLOEC / PM
N/A
1.0
N/A
1.46
Customer Satisfaction
NA
High
Morale (via survey)
N/A
68.1%
Summary
Two characteristically-agile teams:
When used by teams operating within the specified context, the
use of a specified subset of XP practices leads to an
improvement in . . .
Alternative Hypothesis
IBM Case study Sabre case study
evidence?
evidence?
internal code structure
No
No
pre-release quality
Yes
Yes
post-release quality
Yes
Yes
programmer productivity
Yes
Yes
customer satisfaction
Yes
N/A
team morale
Yes
N/A
Conclusions

XP “successful” for two small, co-located teams

“It was the best of times, it was the worst of
times.”
– OK, no “worst times” detected.
– Though some may still yearn for the structure of plan-driven
methods . . . a personal, cultural thing.
Agile Practices Knowledge Base
Breakout Group


What information needs to be in a knowledge base
to provide meaningful resources and information
to researchers and practitioners?
Use XP-EF as baseline
– We know of shortcomings and some areas we are working on
– What else?
– Something different?

Logistics of how such a knowledge base could
work
– OpenSeminar-style (http://openseminar.org)
– Self-moderating, self-refereeing

Do you have any data/experiences to contribute?