A challenge to introduce game theoretical analysis to empirical software engineering / mining software repositories.

1. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Characteristics of Sustainable OSS Projects:
A Theoretical and Empirical Study
!
Hideaki Hata, Taiki Todo, Saya Onoue, Kenichi Matumoto
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2. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015 2

3. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Toward Sustainable OSS
How can OSS projects attract developers?
!
What can OSS projects do to incentivize
developers to write code?
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4. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Context
GHTorrent datasets
• Top-10 starred software
projects for the top
programming languages on
Github: 90 projects
Filtering
• More than 3 year histories
on Dec. 2012: 22 projects
4
Gousios, MSR 2014 Mining Challenge Dataset in GHTorrent

5. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
SW Population Pyramids
• Right: coding contributors
• Left: non-coding (comments, issues) contributors
5
Onoue et al., Software population pyramids:
the current and the future of OSS development, ESEM 2014.
Experience
Developers
3 months
}

6. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Varieties of SPP
GHTorrent datasets
• Top-10 starred software
projects for the top
programming languages on
Github: 90 projects
Filtering
• More than 3 year histories
on Dec. 2012: 22 projects
6

7. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
akka
beanstalkd
blueprint−css
compass
devise
django−cms
django−debug−toolbar
homebrew
http−parser
jekyll
jquerykestrel
MaNGOS
mongo
node
openFrameworks
paperclip
rails
redis
scalatra
ThinkUP
tornado
5
10
15
20
5 10 15 20
# of coding bars
#ofdiscussionbars
Distribution of OSS Projects
7
# of coding bars
#ofnon-codingbars

8. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
akka
beanstalkd
blueprint−css
compass
devise
django−cms
django−debug−toolbar
homebrew
http−parser
jekyll
jquerykestrel
MaNGOS
mongo
node
openFrameworks
paperclip
rails
redis
scalatra
ThinkUP
tornado
5
10
15
20
5 10 15 20
# of coding bars
#ofdiscussionbars
Distribution of OSS Projects
8
# of coding bars
#ofnon-codingbars

9. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
akka
beanstalkd
blueprint−css
compass
devise
django−cms
django−debug−toolbar
homebrew
http−parser
jekyll
jquerykestrel
MaNGOS
mongo
node
openFrameworks
paperclip
rails
redis
scalatra
ThinkUP
tornado
5
10
15
20
5 10 15 20
# of coding bars
#ofdiscussionbars
Distribution of OSS Projects
9
# of coding bars
#ofnon-codingbars
(a)
(c)
(b)
(d)

10. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Introducing
game theory
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11. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Game Theoretical Model
A leader-follower game
• Project: keep (K) or setup (S)
• Developer: write code (C) or
non-coding contribution
(discussion, D)
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developer
project

12. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Results of Equilibrium Analysis:!
Incentivize Developers to Write Code
• Setup: To increase the utility of writing code compared to
the utility of just non-coding contributions, projects need to
setup the development environment, which can decrease
the cost of writing code.
• Mandatory: Employment is a big incentive to write code.
The project itself or other third-parties can select this
option.
• Innovation: Innovations can decrease the cost and may
increase the reward.
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13. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Empirical Analysis
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14. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Coverage of Setup
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TABLE I
COVERAGE OF SETUP
Area Project Wiki Website How to Contribute Coding Guideline Multi-Language Document # of yes
(b)
rails no yes yes no no 2
jekyll yes yes yes no no 3
django-cms no yes no no no 1
jquery yes yes yes yes no 4
paperclip yes yes yes no yes 4
homebrew yes yes yes yes yes 5
node yes yes yes no no 3
tornade yes yes no no no 2
devise yes yes yes no no 3
redis yes yes no no no 2
openFrameworks yes yes no no no 2
compass yes yes yes yes no 4
(d)
mongo no yes yes yes no 3
akka no yes no no no 1
(a)
ThinkUP yes yes no no no 2
django-debug-toolbar yes yes no no no 2
http-parser no no no no no 0
beanstalkd yes yes no no no 2
MaNGOS no yes no no no 1
kestrel yes yes no no no 2
(c)
scalatra no yes no no no 1
blueprint-css yes yes no yes no 3
hosting service and social networking system for developers, have balanced software population pyramids with many coding

15. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Employment
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akka
beanstalkd
blueprint−css
compass
devise
django−cms
django−debug−toolbar
homebrew
http−parser
jekyll
jquerykestrel
MaNGOS
mongo
node
openFrameworks
paperclip
rails
redis
scalatra
ThinkUP
tornado
5
10
15
20
5 10 15 20
# of coding bars
#ofdiscussionbars
# of coding bars
#ofnon-codingbars
25 paid in 116
12 paid in 34

16. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Innovation: Impact of GitHub
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1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
5 0 5
2007/12
1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
200 100 0 100 200
2008/12
1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
200 100 0 100 200
2009/12
1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
200 100 0 100 200
2010/12
1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
700 350 0 350 700
2011/12
1 year
2 years
3 years
4 years
5 years
6 years
7 years
8 years
700 350 0 350 700
2012/12
ategory coding discusscussion movedsion moveddiscussion ategory codingmovediscussioncoding discussionscussion moved
Fig. 7. The transition of software population pyramids of the rails project. This project moved to GitHub on 2008/4
C. The Impact of Innovation the analysis to a bit different situations, such as a new market
with a slight modified pricing rules and/or a social laws.
Rails moved to GitHub on August 2008

17. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Summary
To attract and retain coding contributors
• Prepare documents (setup)
• Have paid developers (employment)
• Adopt new technologies/environment (innovation)
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18. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Discussions
• Limitations in theoretical analysis
• Bounded rationality. Humans are not rational in general
• Too much simplification
• Threats to validity in empirical analysis
• Limited datasets
• Analysis result may have error
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19. Hideaki Hata, Characteristics of Sustainable OSS Projects @ CHASE 2015
Future Directions
• Integration of theory and empirical analysis
is strong approach for
• understanding human behaviors
• designing desirable environments
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