This document discusses pair programming and its benefits. It summarizes research showing that pairs produce higher quality code with fewer defects faster than individuals. Specifically, pairs spent 15% more time but produced code with 15% fewer defects. Additional benefits of pair programming included increased communication, feedback, energy, consistency, focus on team goals, and resistance to pressure to conform to incorrect solutions. While pairing increases productivity, it is still not widely used due to cultural preferences for individual work.

1. pair
programming
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email : jon@jaggersoft.com
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2. a seldom questioned view of
programming - a view which this
book will spend a great deal of
time questioning. That view is
that programming is an
individual activity...
individual
from... (see slide 4)

3. if egoless programming is used,
everyone in the group will have the
opportunity to examine the work of
everyone else at some time, thereby
tending to prevent the establishment
of strong hierarchy.
team
from... (see slide 4)

4. 4
Written 1969
Published 1971
Silver Anniversary 1994
Golden Anniversary 2019
longest continuously
in-print book on software
development?

5. mob
programming

6. we were doing incremental
development as early as 1957...
where the technique used was,
as far as I can tell,
indistinguishable from XP
http://www.craiglarman.com/wiki/downloads/misc/history-of-iterative-
larman-and-basili-ieee-computer.pdf
Jerry Weinberg

7. we worked with punch cards
and printouts... with a
turnaround time of a week or so
as we airfreighted decks of
cards from New York to Los
Angeles.
personal email from Jerry

8. when do
developers
instinctively
pair?

9. rubber-duck
debugging
https://en.wikipedia.org/wiki/Rubber_duck_debugging

10. silenttalking
images are representative only

11. productivity
in my experience,
pair programming is
more productive than dividing the work
between two programmers and then
integrating the results
extreme Programming explained

12. pairs spent about 15%
more time on the
program than the
individuals*
the resulting code
has about 15%
fewer defects
the pairs consistently
implemented the same
functionality in
fewer lines of code
most of the programmers
enjoyed programming
collaboratively
http://collaboration.csc.ncsu.edu/laurie/Papers/ieeeSoftware.PDF
strengthening
the case for
pair programming
Laurie Williams
Robert Kessler
Ward Cunningham
Ron Jeffries

13. an experiment by Temple University...
Professor Nosek studied 15 full-time,
experienced programmers working for 45
minutes on a challenging problem, important
to their organization, in their own
environment, and with their own equipment.
Nosek, J. T. (1998). The Case for Collaborative Programming. Communications of the ACM. March 1998: 105-108.

14. five worked individually, ten worked
collaboratively in five pairs.
Conditions and materials used were
the same for both ... groups.
Nosek, J. T. (1998). The Case for Collaborative Programming. Communications of the ACM. March 1998: 105-108.

15. all the teams outperformed the
individual programmers, enjoyed the
problem-solving process more, and
had greater confidence in their
solutions... producing better
algorithms and code in less time (40%)
Results statistically significant using two-sided t-test.

16. if pairing increases
productivity
why is it rare?

17. pairing is rare
because working
alone is common!

18. "locking" occurs whenever a
situation creates an
environment favorable for
maintaining that situation...
locking occurs in all sorts of
systems... especially... social
Psychology of Computer Programming

19. ? individual assessments
? different keyboards
? different editors
? table design
? room layout
? number of computers
? tools
...

20. pair programming works for XP
because it encourages
communication
XP is a communal software
development discipline.
communication

21. we are all lousy
self evaluators
Switch by Chip and Dan Heath
feedback

22. programmers admit to
working harder and
smarter on programs
because they do not want
to let their partner down
Pair Programming Illuminated
energy

23. risk
pairing helps reduce
truck/bus number
(aka the lottery number)

24. interruptions
pairs are very
resistant to
interruptions

25. interviewing
teamwork characteristics
cannot be determined
if you interview
one at a time.
The Deming Route to Quality

26. i felt it was unwise to allow
players to practice by
themselves. Always I wanted
them to be interacting with their
teammates.
Wooden on Leadership
interaction

27. the pair results were
more consistent...
the individuals varied
more about the mean.
consistency
Pair Programming Illuminated

28. widespread use of pair
programming involves a
cultural shift in values of the
organization - away from
individual and toward team
recognition and goals.
Pair Programming Illuminated
team

29. courage
courage is the capacity
to go ahead in spite of
fear, or in spite of pain.
M. Scott Peck

30. if people program solo they are
more likely to make mistakes,
more likely to overdesign,
more likely to blow off the other
practises, particularly under
pressure
extreme Programming explained
quality

31. Studies of Independence and
Submission to Group Pressure.
A Minority of One
Against a Unanimous Majority
Solomon Asch
Psychological Monographs, 1956.

32. 7 confederates
1 subject
https://en.wikipedia.org/wiki/Asch_conformity_experiments

33. 18 trials
in trial 1 and trial 2 the
7 confederates and the subject
gave the obviously right answer
in the remaining 16 trials the
7 confederates gave the same
obviously wrong answer 12 times

34. 75% of subjects gave the incorrect
answer in at least 1 trial
the subject conformed to the
incorrect answer in all 12 trials
36% of the time

35. Studies of Independence and
Submission to Group Pressure.
A Minority of Two
Against a Majority
Solomon Asch
Psychological Monographs, 1956.

36. presence of 1 true confederate
decreased subjects conformity to the
incorrect answer
by 75%

37. thanks for listening
twitter : @JonJagger
email : jon@jaggersoft.com
blog : http://jonjagger.blogspot.co.uk/
charity : http://cyber-dojo.org
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38. 1969 1990 2004