Economic Science Association World Meetings 2010
Visibility of Contributions and Cost of
Information: An Experiment on
Public Goods
Anya C. Savikhin
Roman M. Sheremeta
The University of Chicago
Chapman University
Vernon Smith Experimental Economics
Laboratory, Purdue University
Motivation
 Recommendation from existing literature for increasing
contributions: recognize all contributors in easily
accessible location (Andreoni and Petrie, 2004; Rege and Telle, 2004)
 Too many contributors and this becomes difficult
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Visibility of Information
 Charities may publicize names of largest donors – this
may also introduce some degree of competition
between contributors concerned about prestige
 Less costly to view
 Donors who contribute small amounts are not recognized
 All names could be publicized but this list is long (Yahoo)
 Costly to view
 All donors (even small amounts) are recognized
 Contribution: Is it more effective to recognize all
contributors (but this information may not be visible), or
recognize only top contributors?
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Experimental Design
 Procedures
– z-Tree 3.3.6 (Fischbacher, 2007)
– Subjects earned $14 each on average (20 francs = $1, 2
periods selected for payment)
– Session lasted for about 45-60 minutes
 Public Goods Game (VCM) (Groves and Ledyard, 1977)
– Fixed matching into groups of 5 participants , same groups for
entire session (20 periods)
– Endowment of 80 experimental francs per period
– MPCR = 0.4
– End of each round: ranked members and display contribution
of each member
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Experimental Treatments
5
(N)
Control (none
shown)
(T)
Only top 2
recognized
(A)
All contributors
recognized
(AC)
All recognized,
costly to view
(3 francs)
40 (2 sessions)
40 (2 sessions)
40 (2 sessions)
40 (2 sessions)
 Digital photos with name to identify subjects to one
another (similar to Andreoni and Petrie, 2004)
Results: Overview
Contribution
N
80%
T
A
AC
70%
60%
 Result 1: A significantly
increases contributions
relative to N
50%
40%
 Result 2: T increases
contributions only
marginally relative to N
30%
20%
19-20
17-18
15-16
13-14
11-12
9-10
7-8
5-6
3-4
1-2
10%
Period
 Result 3: AC does not have
a significant effect on
contributions as compared
to A  with 20 periods and 40 individuals
in the AC treatment, the number of times
photos are viewed is 74/800 (9.2%).
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Leaders, Laggards, Prestige, Guilt
• “Leaders” set an example by contributing a lot
– Any individual who contributed 75%+ of endowment in the 1st period
• “Laggards” contribute little
– Any individual who contributed 25%- of endowment in the 1st period
• Prestige effect: Causes to contribute large
amounts of endowment if I am recognized –
more “leaders”
• Guilt effect: Causes to contribute if my small
amount is recognized – fewer “laggards”
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Prestige and Guilt
(N)
(T)
(A)
Compare to the ✘☝☝Leaders
Baseline (N)
✔ ☝☝Leaders
(Laggards are not
explicitly revealed)
✔ ☟☟Laggards
(AC)
✔ ☝Leaders
☝
✔ ☟Laggards
 Result 4: T not statistically significantly different in leaders
or laggards relative to N
 Result 5: A increases leaders & decreases laggards
relative to N.
 Result 6: AC similar in leaders as A, but significantly more
laggards than A
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Overall Distribution of Contributions
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“Followers”
• The “social interaction effect” increases contributions
of followers given more leaders, and decreases
contributions of followers given more laggards
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Conclusions
• Replicates previous findings that revealing identities
significantly increases overall contributions
• We find that display of all information, even if it is
costly to view, is more effective than displaying only
top contributors
– By increasing proportion of leaders and decreasing
proportion of laggards
– This causes contributions by followers to increase
• Designers of online community groups and charities
should display full information, even if it is costly to
view
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