This is Part 2 of the Nudge Database.
Part I|| Part III|| Part IV|| Part V || Part VIPart VII@Makeuya
authors ran a trial on Facebook using social
proof to induce people to vote during the 2010 U.S. Congressional
Elections. Treatment Group 1 contained 60 million people who saw a neutral ‘get
out the vote’ ad along with a clickable “I voted” button. Treatment group 2
contained 600,000 people who saw an ad (pictured) embedded with a social proof
element showing which of their friends had voted. The Control group contained
600,000 people who received no imploration to vote.
The results showed that users
who received the social message were more likely to have clicked “I voted”. While
Treatment Group 1 and the Control group had the same turnout rates, Treatment
group 2, which implemented the social proof mechanism, had significantly more turnout
rates. The researchers estimate that the direct effect of the Facebook social
message on users who saw it generated an additional 60,000 votes and the
effects of the social network – of social contagion among friends – yielded
another 280,000 more, for a total of 340,000. In other words the social network
yielded an additional four voters for every one voter that was directly
mobilized. To verify whether the participants really did vote rather than just
claim they the authors compared turnout rates among their treatment &
control groups and found 4% of those who said they voted had not.
Tags : voting / social proof / facebook
Source: Bond et al. (2012), 'A 61-million-person experiment in social influence and political mobilization', Nature.
Writeup here, worth reading in detail.
Nudge: Using financial
incentives to encourage prosocial
behavior by levying a 5 cent tax on
plastic bags in Washington D.C.- Despite the trivial fee, it had a significant
effect on disposable bag use. A similar policy that offered a 5 cent bonus had
no significant effect on behavior. In the graph note the before/after effects
in Montgomery County of introducing the tax.
Tags : social norms / plastic bags /
Source: Homonoff (2012) 'Can Small Incentives Have Large Effects? The Impact of Taxes versus Bonuses on Disposable Bag Use', Job Market Paper.
Nudge: Direct mail field experiment in
South Africa which randomized advertising content about loans to measure the effects
of different framing on demand. Found several interesting
things, e.g. including a photo of a pretty girl increased loan demand by as
much as if you had reduced the interest by 25% of the original rate.
Tags : framing / loans / advertising
Bertrand et al. (2010), ‘What’s Advertising Content Worth? Evidence from a Consumer Credit Marketing Field Experiment’, The Quarterly Journal of Economics.
Nudge: Three field experiments looking
at increasing savings with text message reminders.
Goal-specific reminders were
considerably more effective than generic ones, resulting in a 16% increase in
savings compared to 6% for the generic reminder and 0% for the control which
received no reminders.
Tags : inter-temporal choice /
present-bias / text messages / savings
Source: Karlan et al. (2010), 'Getting to the Top of Mind: How Reminders Increase Saving', NBER Working Paper.
Nudge: Encouraging Kenyan farmers to
match their actions with their intentions regarding their use of fertilizer by mitigating their present-bias & procrastination
tendencies through improved behavioral design. Specifically, treatment groups
received a visit from an NGO officer offering them vouchers to buy fertilizer
in the future and offers to deliver it for free, though this would be
prohibitively expensive to do on a large scale. Although the treatment group
purchased significantly more fertilizer, read the conclusion for important
limitations of the study.
Tags : present-bias / self-control /
time-discounting / fertilizer
Source: Duflo et al. (2010), ‘Nudging Farmers to Use Fertilizer : Theory and Experimental Evidence from Kenya’, American Economic Review.
Nudge: Two treatments offered ‘ordinary’
and ‘ordinary & commitment’ savings
accounts to Malawian farmers. Commitment accounts allowed savers to restrict
access to their own money until
a designated date. Control group was not offered any account. Only commitment
accounts had significant impacts on savings, later allowing those people to
purchase 26% more agricultural inputs than the Control.
Tags : time-discounting / self-control /
commitment / savings
Source: Brune et al. (2011), 'Commitments to Save : A Field Experiment in Rural Malawi', World Bank Policy Research Working Paper.
manipulating the position of food on a restaurant menu. Found items placed at
the beginning or end were found to be up to twice as popular as when the same
items were placed in the centre of the menu.
Tags : obesity / position effects
Source: Dayan & Hillel (2011), 'Nudge to nobesity II: Menu positions influence food orders', Judgment and Decision Making.
Nudge: Automatically enrolled employees
into a 401(k) plan, finding that the default was incredibly sticky both in
terms of how many people did not opt out of it & how many people stuck with
the automatic savings rate. The latter issue, potentially problematic if people
did not save enough, was later tackled by ‘Save More Tomorrow’.
Tags : defaults / inertia / savings
Source: Madrian & Shea (2001), 'The Power of Suggestion: Inertia in 401(k) Participation and Savings Behavior', The Quarterly Journal of Economics.
child immunization in India with
small incentives. 34 villages were randomly divided into 3 groups. A
& B were treatment groups, C was the control.
monthly immunisation camp;
monthly immunisation camp with incentives (raw lentils & metal plates for
Group B outperformed A in achieving full immunization by a factor of two.
Tags : immunization / incentives
Source: Banerjee et al. (2010), ‘Improving
immunisation coverage in rural India: clustered randomised controlled
evaluation of immunisation campaigns with and without incentives’, British Medical Journal.