the benefits of pair programming
DESCRIPTION
The Benefits of Pair Programming. Robert Kessler School of Computing University of Utah Special thanks to Laurie Williams North Carolina State University. What Is Pair Programming?. - PowerPoint PPT PresentationTRANSCRIPT
CS 3500
L12pp - 1
The Benefitsof Pair Programming
Robert Kessler
School of Computing
University of Utah
Special thanks to
Laurie Williams
North Carolina State University
CS 3500
L12pp - 2
What Is Pair Programming?
"Pair programming is a simple, straightforward concept. Two programmers work side-by-side at one computer, continuously collaborating on the same design, algorithm, code, and test. It allows two people to produce a higher quality of code than that produced by the summation of their solitary efforts."
CS 3500
L12pp - 3
This Is Pair Programming
CS 3500
L12pp - 4
This is NOT Pair Programming
CS 3500
L12pp - 5
Pair Programming Has Been Around For a LONG TIME!
. . . 1945 1953 … 1997 1998 1999 2000 2001 2002
John von Neumann, recognized his own inadequacies and continuously asked others to review his work.
Fred Brooks and many others are pair programming, though they don’t know there is a name for it.
CS 3500
L12pp - 6
Does Pair Programming Really Work? Empirical study by Laurie Williams at the university
of Utah Practice: Summer 1999
– 20 students (sophomore/junior)» All worked collaboratively
– Generated more anecdotal/qualitative evidence
Solo vs. pair: Fall 1999– 41 students (junior/senior)
» 28 worked collaboratively» 13 worked individually
– Software development process was controlled» The only experimental variable: pair-programming
– Quantitative: time, quality, enjoyment, confidence
CS 3500
L12pp - 7
Post Development Test Cases Passed
0.0%10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%
100.0%
Program 1 Program 2 Program 3 Program 4
Individuals
Collaborators
Findings #1 - Quality
CS 3500
L12pp - 8
Elapsed Time
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
120.0%
Program 1 Program 2 Program 3
One Individual One Collaborator
Findings #2 - Time
CS 3500
L12pp - 9
Enjoy the Work More Because of Pair Programming
0%
20%
40%
60%
80%
100%
PROF SUM1 SUM2 SUM3 FALL1 FALL2 FALL3
Agree Disagree
More Confident in our Work When Pair-Programming
0%
20%
40%
60%
80%
100%
PROF SUM1 SUM2 SUM3 FALL1 FALL2 FALL3
Agree Disagree
Findings #3 and #4 – Enjoyment and Confidence
CS 3500
L12pp - 10
How Does This Work?
Pair-Pressure– Keep each other on task and focused– Don’t want to let partner down– “Embarrassed” to not follow the prescribed process – Parkinson’s law “work expands to fill all available time.”
Pair-Think– Distributed cognition: “searching through larger spaces of alternatives”
» Have shared goals and plans» Bring different prior experiences to the task » Different access to task relevant information » Must negotiate a common shared of action
Pair-Relaying– Each, in turn, contributes to the best of their knowledge and ability– Then, sit back and think while their partner fights on
CS 3500
L12pp - 11
How Does This Work (Part Two)?
Pair-Reviews– Continuous design and code reviews– Ultimate in defect removal efficiency– Removes programmers distaste for reviews
» 80% of all (solo) programmers don’t do them regularly or at all
Debug by describing– Tell it to the Furby
Pair-Learning– Continuous reviews learn from partners techniques, knowledge of
language, domain, etc.– “Between the two of us, we knew it or could figure it out”– Apprenticeship– Defect prevention always more efficient than defect removal
CS 3500
L12pp - 12
Research Findings to Date - 1 Strong anecdotal evidence from industry
– “We can produce near defect-free code in less than half the time.”
Empirical study– Pairs produced higher quality code
» 15% less defects (difference statistically significant)
» Observed – pairs produced smaller (LOC) programs
– Pairs completed their tasks in about half the time» 58% of elapsed time (difference NOT statistically significant)
– Most programmers reluctantly embark on pair programming» Pairs enjoy their work more (92%)
» Pairs feel more confident in their work products (96%)
CS 3500
L12pp - 13
Research Findings - 2 Several educational studies underway
– University of California, Santa Cruz; North Carolina State University
– What about pair learning?
» Anecdotal says that it works well
– What are the long-term issues?
» If you learn as a pair, can you work as a solo?
Distributed pair programming studies underway– North Carolina State University; University of North Carolina-Chapel Hill
– Early results: distributed pair programming is viable
– My experience:
» Need to meet and know your pair
» Need a good tool like VNC and telephone
» Video not important
CS 3500
L12pp - 14
Issues: Workplace Layout
Bad Better
Best
CS 3500
L12pp - 15
Issues: Partner Picking Principles
Expert paired with an ExpertExpert paired with a Novice
Novices paired together Professional Driver Problem Culture
CS 3500
L12pp - 16
Issues: Pair Rotation
Ease staff training and transition
Knowledge management/Reduced product risk
Enhanced team building
CS 3500
L12pp - 17
Expected Benefits of Pair Programming
Higher product quality
Improved cycle time
Enhanced learning
Pair rotation– Ease staff training and transition
– Knowledge management/reduced product risk
– Enhanced team building
Increased programmer satisfaction
CS 3500
L12pp - 18
More Information
Laurie [email protected]
http://pairprogramming.com http://collaboration.csc.ncsu.edu/laurie